When renowned classical cellist Yo-Yo Ma teamed with three legendary bluegrass musicians, no one knew what would happen — that's why Ma and bandmates called it "The Goat Rodeo Sessions."

The idea is that the project was like herding goats — a big chase where everything has to go right for it to work, fiddler Stuart Duncan said in an interview with The Press Democrat earlier this month. The ensemble plays tonight (Aug. 23) with vocalist Aoife O'Donovan (Crooked Still) at the Green Music Center in Rohnert Park.

Given the talent in the band — Edgar Meyer on bass, Chris Thile (Nickel Creek) on mandolin and Duncan on fiddle — it's not surprising that it all worked beautifully. The poignancy and pristine technique of Ma's cello blends seamlessly with the lively down-home artistry of his Americana cohorts.

But don't think for a moment that this is Ma with a supporting band — each musician is at the top of his game and plays a prominent role.

"Everybody could be a leader or everybody could be a follower at various times," Ma said during an NPR interview in late 2011, when the album was released. "And I think the vast amounts of fun that we have — which is, for me, that's the goat rodeo part: How can we ever get any work done when we're laughing all of the time?"

It's an alchemical combination, with the classical influences informing the bluegrass, and the old American music getting Ma to put on some dusty boots and kick up his heels.

"Our desire was to create music that you couldn't necessarily tell if it was composed or improv," Duncan said during a conversation and concert at Google in 2011.

Thile had played with Ma prior to the Goat Rodeo Sessions and asked Duncan to join the band.

"Most of me was going, 'Are you kidding, yes!,' but there was this big part of me that was going 'I don't know — how is this going to work?'" Duncan said.

When he learned they'd have nine months to experiment and write the songs, Duncan signed on.

"You can do anything with a little a bit of time," he said, "so we just started writing."

For Duncan, who has been touring this year with Diana Krall, the boundary-stretching aspirations of the Goat Rodeo project suited him perfectly.

"I've always gotten bored easily with my own playing, which has led to me listening to something and saying, what's this about and how can I weave some of this influence into some of the things I do without it seeming like I've gone over a cliff," he said.

"How can I borrow some of that and make it still musical? I've always been chasing that way of looking at music — this is everything I was hoping for times 10."

Asked if the project has been fun for Ma, Duncan said: "Either that or he's that cheerful and excited all the time. Hopefully, that means he's having a good time."

Duncan doesn't read music, a stark counterpoint to the studious Ma. "The band has two handicapped players in it: Yo-Yo doesn't improvise and I don't read," Duncan said.

"Since then, I've heard Yo-Yo improvise — he's very capable of it, but that was the ongoing joke for a while."

The Goat Rodeo Sessions launched in late 2011, and Duncan senses the band is coming to the end of its run, so tonight's show (8/23) could be Goat Rodeo's last appearance in the North Bay.

"It's a very short tour," said the in-demand session musician. "I would love for it to continue, but finding the time, perhaps that's the greatest obstacle."

Yet you never know what will happen when the music takes on a life of its own. Duncan says a Goat Rodeo children's album could be the next step.

"It would be great to do a second project: Yo-Yo's idea is to do a children's record, but I'm not sure we're the guys for that," Duncan said. "But with the sense of humor in this band, I think we'd have more fun doing that than anything else."

Michael Shapiro writes about entertainment for The Press Democrat. Contact him at michael.shapiro@pressdemocrat.com or see his site: www.michaelshapiro.net.