Leo Kottke and Mike Gordon know they are a musical odd couple. Nailing down what makes their ongoing partnership a success is a little trickier.

“We really don’t talk much about how this is or why it works for us,” Kottke said recently from his home in Minneapolis as the duo prepared for a fall tour to support their second album, “Sixty Six Steps.” “We’ll just start playing. … It’s more like a dream that’s coming forward.”

Somehow, their personalities have clicked, said Gordon, the former Phish bassist, from his Burlington, Vt., home. “People who know us both well say ‘Oh yeah, of course. You’re both some real oddballs.’ I see it as following some pretty deep gut feelings.”

The pairing is a departure for both Kottke, who turns 60 in September, and Gordon, 40.

Until his first tour with Gordon three years ago, Kottke had never hit the road with a bassist. He made his name through complex, syncopated six- and 12-string guitar playing and smartly crafted tunes. His more than two dozen albums have run the gamut from folk, jazz, blues and film music.

Phish was the premier jam band of its generation, known for their extended improvisational style, which garnered a massive, dedicated following during years of steady touring.

When Phish broke up last summer, Gordon didn’t think twice about calling up Kottke to record a follow-up to their initial effort, 2002’s “Clone.”

“It’s like he’s a key that gets in there and unlocks part of my playing or sensibility as a musician that is there all the time but it’s locked up,” Gordon said. “Just the fact that he’s willing to do the whole collaboration with me amazes me. He’s so content. He’s got such great fans when he’s by himself.”

Twenty years ago, Gordon learned how to play a Kottke song note by note, never dreaming that one day they would be sharing a stage together.

“I think somebody could have imagined that Mike would have been taken with Leo’s work, but not that there would have been a reciprocal side,” said Dean Budnick, senior editor of Relix magazine, editor of jambands.com and author of “The Phishing Manual: A Compendium to the Music of Phish.”

“It certainly is a collaboration that somewhat gets to the heart of what made the Phish experience so exciting, which is pushing bounds,” Budnick said. “Playing with Leo grounds Mike but also pushes him in a new direction.”

The two teamed up for the first time after Gordon sent Kottke a tape of his bass playing over one of Kottke’s songs. Their first record was a mixture of originals and covers that won favorable reviews for Kottke’s intricate guitar work and Gordon’s offbeat songwriting.

“I haven’t really been missing the Phish experience, which is strange because I’m in love with the Phish experience that I had,” Gordon said. “It’s been a very easy grieving process but I don’t really know why.”

The four Phish members have met, but they haven’t played as a group – even privately – and there’s no talk about reforming the band any time soon, Gordon said.

For now, Gordon and Kottke are grooving off their partnership.

“It is another universe. … It’s encouraging to find out that you can still flex,” Kottke said. “I did have the hunch that I had probably developed some rock-hard habits by now. But it’s not like that at all.”

Kottke is well respected by other musicians and hardcore music fans. He was listed as the favorite acoustic guitar players by readers of Acoustic Guitar Player magazine in its July issue, beating such luminaries as Eric Clapton, Django Reinhardt and Jimmy Page.

When playing the guitar, Kottke said he is transported to a different place.

“Sometimes you see that place dimly, and you work on whatever you’re working on to see it better,” Kottke said. “I really can just go running around in it when Mike and I are playing.”