When Chinese concert pianist
Zimmer asked Lang whether the score sounded "Asian enough."
"I'm like, 'I don't know where you got it, but you have an Asian heart,' " Lang recalled, laughing.
Lang had been a "superfan" of Zimmer's from the moment he saw "Gladiator." The pianist was 18 when Ridley Scott's epic came out featuring Zimmer's popular, Oscar-nominated score. They've remained friends since that first meeting.
So it shouldn't be too surprising that Lang, now 33, would lend his fingers to Zimmer's latest soundtrack — even if it is for the kid flick "Kung Fu Panda 3."
On an afternoon in October, Lang visited Zimmer's Santa Monica studio and recorded a few piano solos in the composer's cozy work space. A small statue of Po the panda sat on a grand piano, and Lang exhibited his usual showmanship moving from a solemn melody to a high-spirited action cue.
"I feel very kung fu!" he chirped after pounding a series of rapid arpeggios.
The German-born Zimmer co-scored both previous entries in the DreamWorks franchise and invited Lang because he wanted "performers who know what they're talking about ... as opposed to some guy from Frankfurt."
The 58-year-old composer, a 10-time Academy Award nominee and an Oscar winner for "The Lion King," said it's something he always likes to do.
"The only way you can really connect with a culture is to be respectful of the people who actually are that culture and play from that culture," he said.
Lang squeezed the brief session into a typically busy season, having just released a new album ("Lang Lang in Paris") and opened the New York Philharmonic's 2015 season. A few days later he flew to Cuba to perform with the National Symphony Orchestra of Cuba in a historic, cross-cultural concert.
He dismissed the idea that he might be stooping, artistically, to contribute to a movie about a dumpling-munching panda voiced by Jack Black.
"I am taking myself seriously, because the music itself, what Hans created, is great," Lang said. "Let's not talk about whether 'serious' or 'lower' — it's great music."
Zimmer learned to take animation seriously in 1994 when he scored "The Lion King." He admitted that he initially signed up for the job only "because I wanted to show off to my daughter."
"I could never take her to a premiere because she was 6, and you can't really take her to 'Black Rain,'" he said. "So I thought, oh, I'll do a fuzzy animal movie. There I am, working, not taking it very seriously, when suddenly I realize it's about the death of a father. My father died when I was 6 years old — so suddenly, all this stuff I had never dealt with I had to deal with."
The great thing about animation, he added, is it's "our modern-day fairy tale. It can serve a deep psychological need, and it can tell a story the way you just can't in live action. And you better take it seriously."
"Kung Fu Panda 3" opened with $41.3 million in ticket sales last weekend and is expected to finish No. 1 again this weekend. Setting aside its box-office prowess, Lang said he found inspiration in the movie.
"It's not only just fun, but it also shows a lot of deepness and a lot of Chinese culture," Lang says. "Like talking about qi. You can become a kung fu person, but you can also become a musician basing the same kind of technique — air, control, inner peace."
Lang and Zimmer joined Pharrell Williams onstage at the Grammys last year for a genre-mashing arrangement of Williams' song "Happy." Zimmer said the idea was to be multicultural, to prove that "we can actually, truly, play nice."
"Here I am," Zimmer said, "a foreigner in America writing about China, working with a Chinese musician. It's this idea of figuring out how to communicate across the world — which, weirdly, for Lang Lang and I is much simpler than for most other people."
Well respected in concert halls around the world, Lang has long kept one hand in pop culture, performing with Metallica and on other film soundtracks. He likes to remind people that his introduction to classical music came via "Tom and Jerry."
Zimmer said he wants to compose a new work for Lang someday. ("We should just go away somewhere," he said to Lang, "like Capri or somewhere nice — four weeks just a piano and us — and write something.")
One of the things he loves about the pianist is his playfulness.