Different genres, different generations, both virtuosos

Even by the hyper-individualistic standards of the piano world, jazzman Herbie Hancock and classicist Lang Lang are as unorthodox as duo-piano pairings get. Put them together with the almost-never-heard Ralph Vaughan Williams Concerto for Two Pianos and Orchestra, and Thursday's final program of the Philadelphia Orchestra's Mann Center season also has the greatest curiosity factor.

What makes the most sense is the pair's collaboration on Gershwin's Rhapsody in Blue. They played an abbreviated version on the 2008 Grammy Awards telecast and are now touring Europe and the United States, using it as a jumping-off point for improvisation.

But as effortless as these concerts may look, Hancock readily admits, "We're kind of pushing each other over the edge." He's getting used to following a classical conductor, while Lang Lang is acclimatizing to jazz fans who applaud solos in the middle of a piece.

Their genre and age differences - Lang Lang is 27, Hancock is 69 - are apparent in their degrees of trepidation: Though jazz pianists such as Keith Jarrett have crossed over into classical, Hancock, who has recorded 50 jazz albums and won 12 Grammys, feels at a disadvantage because he hasn't played this kind of music since he was a kid growing up in Chicago. But for Lang Lang, Hancock's having once played classical, even that long ago, is all the more reason to do it now.

On Lang Lang's side, jazz is a huge blind spot - almost unknown to his generation in China - and his own classical training at the Curtis Institute of Music was about sticking to the score, though the excitement he brings to that endeavor has made him one of the top classical pianists in the world. Yet, with Lang Lang's chops and musicianship, Hancock sees every reason for him to give improvisation a try.

The experiment began on one of the early European tour stops when Lang Lang "took themes from Rhapsody in Blue and created something that I improvised over," says Hancock. "I didn't know he was improvising at first. I thought it was some piece of Gershwin's that I wasn't familiar with. And it was great. Sometimes, you fall a few times before you get it right. He didn't fall."

"It's like making conversation," says Lang Lang. "You hear what people are saying to you, and then you answer them, while also making a new question. It's much more fun with two people."

Both these musical stretches were perhaps lying in wait. The dreamier passages in the Vaughan Williams concerto are so uncannily similar to Hancock's trademark harmonies that you'd swear the composer and pianist were telephone pals - though they lived in different hemispheres and in lifetimes that overlapped only 14 years. Lang Lang has long played classical music with the animation of a jazz or pop musician.

And Hancock is exactly the kind of elder-statesman musician Lang Lang cultivates in ongoing relationships. Though their pairing on the Grammy Awards looked gimmicky, the two seem to have found in each other what they needed.

"We had this chemistry. We decided to tour," said Lang Lang. "The touch he has, the softness, that very sensitive legato takes a real master to play." Lang Lang particularly admires Hancock's Grammy-winning album River: The Joni Letters and, in one of his encounters with Aretha Franklin, his ability to accompany singers.

Hancock had often been seen at Lang Lang concerts even before their Grammy gig. Together, they hammered out a formal tour beginning July 5 at the Montreux Jazz Festival in Switzerland - hopscotching around Lang Lang's previous straight-classical commitments, which is why, midtour, they conducted separate phone interviews from different German cities.

So it's appropriate that repertoire questions had to be hammered out in international conference calls - hardly a two-piano concerto went unconsidered - with MP3 files sent in all directions.

Hancock connected with Ravel's Mother Goose suite, but most especially with the Vaughan Williams, not knowing that it was so rarely heard that orchestras have had trouble acquiring the individual parts. And though Vaughan Williams is the most genial of composers, his music is deceptively tricky.

"He doesn't indicate exactly what the tempos are supposed to be," said Hancock.

"He liked to switch rhythms in every second bar," said Lang Lang. "It's awkward . . . but when you play on the right track, it's pretty interesting."

Hancock's word of choice might be more along the lines of drudgery as he learned the piece over three months. Even when playing classical concertos - as a child, he performed Mozart with the Chicago Symphony Orchestra - Hancock usually practiced only an hour a day, never more than two. Also, his break with classical music sounded like something akin to a religious epiphany.

"I wanted to be able to play one note, and play the right one, and play it with heart. That's my primary concern," he said. "So the idea of completely reading what somebody else wrote and all that involved - well, I haven't had to do that for years. . . . The first couple of days were not fun. But by the third day, I liked it. I started to feel progress and started to get those almost-forgotten classical juices going in my body."

The impact these experiences are having on both musicians is hard to access at this point. Hancock says he plays jazz "with a little more precision, because my chops are really up," though the kind of collaborations that await him - an album titled The Imagine Project with musicians from India and Mali - are not likely to be directly affected by Vaughan Williams or Ravel.

Lang Lang isn't always happy with cadenzas in Haydn concertos; he could be talked into composing his own from a series of improvisations.

Critical reaction has been a bit mixed. Of the Royal Albert Hall performance, the Daily Telegraph loved the Vaughan Williams - "Both pianists seemed genuinely to love the piece, a fascinating amalgam of Frenchified polytonal glitter with a mystical yearning," wrote critic Ivan Hewett - but the rest has been questioned for a variety of reasons, from taste to audibility.

Neither party is in a great hurry to record the collaboration, even though the commercial value, particularly in the wake of the tour, probably would be considerable. Lang Lang in particular doesn't see this as a one-time-only event.

"I'd could tour with him every day. I really love him as a person," he said. "But we're not a marketing tool. I did this because I really admire Herbie. We did it as a natural process, as friends, and through this project, we're finding new repertoire for classical and jazz. This is tryout. We wouldn't think of making a recording right away."

Herbie Hancock/Lang Lang

8 p.m. Friday at the Mann Center for the Performing Arts, 5201 Parkside Ave. Tickets: $10-$50. 215-893-1999, www.manncenter.org