MLS will kick off the season Saturday with 10 matches, followed by two more Sunday, including D.C. United against reigning champion Atlanta United at Audi Field in Washington.

As the 24th season commences, here is a look at 24 story lines:

1. A 24th season needs a 24th team, right? Welcome FC Cincinnati, which, amid record-smashing attendance in three second-division seasons, organized the financial muscle and stadium plan to win an expansion berth. The newbies will continue playing at Nippert Stadium, a football facility on the University of Cincinnati campus, until a West End venue accommodating at least 25,500 opens in 2021. The Ohio rivalry with the Columbus Crew already has a great name: Hell Is Real Derby.

2. Expansion teams can only dream of impacting the league the way Atlanta has. Two years since its birth, the club has won an MLS Cup, demolished attendance records, won over a major city through branding and stylish performances, and embraced the international transfer market by selling Miguel Almiron this winter for $27 million after purchasing him two years ago for $8.5 million. To replace him, the club acquired Pity Martinez, the South American player of the year at River Plate.

3. A year ago, with its primary investor eyeing Austin, Texas, for relocation, Columbus was on its last wobbly legs as an original MLS market. However, through grass-roots efforts, litigation by the state and new buyers, the Crew was saved. Anthony Precourt will still get a team in Austin, starting in 2021, but he has passed the Crew to a group headed by the Haslam family (which owns the Cleveland Browns) and team physician Pete Edwards. A new downtown stadium is in the works.

4. For the fifth time in three seasons, MLS will christen a new stadium as 19,400-seat Allianz Field opens on the site of a former municipal bus depot in St. Paul, Minnesota. While the venue was constructed, Minnesota United played two seasons at the University of Minnesota's football stadium. The new place was privately financed at a cost of $150 million. The field is natural grass and 85 percent of seating is under cover. No seat is more than 125 feet from the field. The debut is April 13.

5. Perhaps the most important matchups of the season will come not on the field but in conference rooms, where representatives from the league and players' association will seek to reach a collective bargaining agreement. The current pact will expire at the end of the year, and, if the last round of negotiations (in 2015) is any indication, a new deal will not be ironed out until next season is about to start. Broader free agency and minimum salaries are sure to be among the hot topics.

6. Although MLS is trending younger, the league continues to sign high-profile players in their latter years. Which isn't such a bad thing when those players last year were Wayne Rooney and Zlatan Ibrahimovic. Rooney's midseason arrival helped resurrect D.C. United's fortunes, while Ibrahimovic was a phenom on and off the field for the Los Angeles Galaxy. Combined age: 70. Combined stats: 47 matches, 34 goals, 17 assists. Rooney arrived too late last year for the teams' only meeting, but this season, they will collide Aug. 11 in Washington.

7. In a few weeks, when the trivia question is asked - Who is MLS's all-time leading scorer? - the answer will barely register outside league circles. But with two more goals, raising his regular season total to 146, San Jose's Chris Wondolowski, 36, will surpass former U.S. national team star Landon Donovan for the career record - an extraordinary feat for an NCAA Division II forward who was selected in a supplemental draft and started 19 games in his first six seasons. Since 2010, he has averaged 15.2 goals, with a high of 27 in 2012, when he was voted MVP.

8. Colorado Rapids goalkeeper Tim Howard has announced he will retire at the end of the season - a final campaign in a phenomenal career that began in 1998 with the New York/New Jersey MetroStars and included 13 years in the Premier League with Manchester United and Everton. He also started in two World Cups, highlighted by an extraordinary performance against Belgium in 2014. A once-sterling skill-set, though, has eroded and, with his 40th birthday next week and his national team career over, the time will soon come for others to save the day.

9. MLS has made strides signing not only renowned players, but well-known coaches. This season marks the arrival of Atlanta's Frank de Boer, a former Dutch star who has guided Ajax, Inter Milan and Crystal Palace. The Galaxy hired Guillermo Barros Schelotto, the 2005 MLS MVP who, as a coach, inspired Boca Juniors to two Argentine titles and the Copa Libertadores final this winter. San Jose pulled a major surprise by drawing Matias Almeyda from Chivas Guadalajara, the 2018 Concacaf Champions League winner.

10. MLS also lost three successful coaches to prominent positions as Gregg Berhalter departed Columbus for the U.S. national team, Gerardo Martino moved from Atlanta to the Mexican national team and Oscar Pareja left FC Dallas for Mexican club Tijuana.

11. Dallas took a unique tack in its coaching search, staying in-house and hiring Luchi Gonzalez, the organization's academy director. Under his influence, Dallas has signed 15 homegrown players since 2012 and won several national championships at the under-17 and under-19 levels.

12. The Portland Timbers might want to seek advice from D.C. about navigating a strange schedule. A year after United played 12 of its first 14 matches on the road - and used alternative venues for those two home dates while Audi Field was being erected - the Timbers will face 12 away games to start the season because of ongoing renovations at Providence Park. The project will expand capacity by 4,000 to around 25,000. They will not host a match until June 1.

13. MLS has never been able to get the playoff formula just right, forever tinkering with formats and schedules and taking two-week breaks for national team matches. No wonder each year many casual fans weren't sure whether the postseason was still going on. The league will take another crack at it this year: seven teams instead of six from each conference; one team, instead of two, receives a first-round bye; and all matchups are single games, instead of some being single and some two legs.

14. Besides trying to fix the playoffs, MLS felt the season was too long. So it will pack the same number of regular season games (34 per team) into a calendar that's three weeks shorter. That, combined with the streamlined playoff format, allows MLS Cup to be played Nov. 10, a month earlier than last season. No more fretting about freezing conditions in Toronto or Kansas City. The new schedule also works well with FIFA's international breaks, which fall immediately after the regular season and postseason end.

15. Many leagues around the world are dominated by big-spenders who, in hoarding trophies, create a great divide with the rest of the circuit. MLS's financial guidelines prevent vast payroll differences. That guardrail, along with the unpredictability of short playoff duels, has resulted in 10 clubs winning the past 12 MLS Cups. With three crowns in that time, the Galaxy is the only one to win multiple championships. Since 1996, only the Galaxy (five) and D.C. (four) have claimed more than two titles. Atlanta enters 2019 as the favorite, but given MLS's trends, someone else is likely to win it.

16. Last year at this time, Toronto FC was a good bet to win a third consecutive Eastern Conference title, repeat as MLS Cup champion and possibly become the first league representative to claim the Concacaf Champions League crown. But after coming within a whisker of beating Chivas Guadalajara, the Reds never rediscovered their groove and missed the playoffs. This winter, they sold 2015 MVP Sebastian Giovinco (68 goals, 52 assists in four years) to a Saudi club and Victor Vazquez (25 assists in two years) to a Qatari side. Striker Jozy Altidore is returning from an ankle injury that contributed to him starting just 12 times in 2018. This week he signed a three-year contract extension, but Michael Bradley is in the last year of his contract.

17. Giovinco was not the only star to leave MLS. Spain's David Villa, 37, completed a four-year run with New York City FC after posting 77 goals. He is now playing in Japan. Big transfer fees led to the sale of Almiron to Newcastle; New York Red Bulls midfielder Tyler Adams, 20, to RB Leipzig; Vancouver Whitecaps forward Alphonso Davies, 18, to Bayern Munich; and, effective this summer, Columbus goalkeeper Zack Steffen, 23, to Manchester City. Bayern paid a smaller amount for Dallas defender Chris Richards, 18, and the Galaxy sold forward Ola Kamara to a Chinese team.

18. Besides Atlanta buying Pity Martinez, the international market yielded two other prominent players: Orlando City signed Sporting Lisbon attacker Nani, whose best years were with Manchester United, and the Philadelphia Union acquired Mexican attacker Marco Fabian from Eintracht Frankfurt.

19. The transatlantic influx of U.S. players saw Toronto acquire Terrence Boyd (Germany) and Quentin Westberg (France), Cincinnati ink Kekuta Manneh (Switzerland) and Caleb Stanko (Germany), New York City grab Keaton Parks (Portugal) and Juan Torres (Belgium), Orlando take Alex De John (Sweden), Los Angeles FC sign Alejandro Guido (Mexico) and Atlanta sign Brendan Moore (England).

20. There was flow the other way, as well, namely to Scotland: Chicago lost homegrown defender Andrew Gutman, the Hermann Trophy winner from Indiana, to Celtic, which also claimed North Carolina State's Manny Perez. Former Chicago defender Matt Polster (Rangers) and ex-D. C. midfielder Ian Harkes (Dundee United) also ventured to Britain.

21. Free agency is in its infancy in MLS, paling in the impact and intrigue that grips the NBA, NFL and MLB. To qualify, a player must be at least 28 and have logged eight seasons in MLS. Although there were no high-impact players available, Minnesota (Osvaldo Alonso) and Colorado (Benny Feilhaber) were the winners. Alonso, a tenacious midfielder, played 10 years for Seattle, while Feilhaber had spent one year with Los Angeles FC after a fruitful stay in Kansas City.

22. Don Garber ranks second behind the NHL's Gary Bettman in seniority as a commissioner and, by signing a new contract this winter, he will remain in charge of MLS through 2023. This August will mark the 20th anniversary of his hiring from the NFL, a period marked by the doubling of teams, soaring valuation of its clubs and a stronger foothold in a global sport. Garber, 61, reached a personal high of No. 16, one slot behind LeBron James, in the Sports Business Journal's list of the 50 most influential people in the industry last year.

23. Key dates: MLS teams have the flexibility to continue signing players until May 7. The prime opportunity to make improvements, particularly from abroad, comes in the secondary transfer window, July 7-Aug. 7. The All-Star Game, to be held in Orlando, will take place July 31, with a select MLS squad facing an international opponent to be announced. (Last year, it was Juventus.) The 21 U.S.-based teams will begin the U.S. Open Cup - a 105-year-old tournament mixing all levels of American soccer - in the round of 32 on June 12. Houston is the defending champion.

24. MLS will go dark June 9-21 - for regular season matches, at least - as the Concacaf Gold Cup commences. Most of the 16 participating national teams will pull players from MLS. Players will begin reporting before the MLS break. Additionally, some MLS players from South America will depart for Copa America in Brazil, June 14-July 7, and others will head to the Under-20 World Cup in Poland. The Gold Cup and Copa America require clubs to release players, but the U-20 event does not.