If Avril Lavigne's second album -- due in stores May 25 -- does as well as her first, she'll owe a big thank-you to Chantal Kreviazuk.

Last summer Kreviazuk took her fellow Canadian singer-songwriter under her wing at her Malibu home, teaching the Napanee teenager some piano licks and writing a bunch of songs with her. The two formed a solid relationship of mutual respect and sisterhood, despite more than 10 years difference in age (Kreviazuk will turn 30 in May).

"Sometimes, she was my muse. She was a 19-year-old, so I'd go into her space and then it would build from there," says Kreviazuk, who was born and raised in Winnipeg. "Sometimes, she would be the mature one and we would flip back and forth and change our roles with each other."

The pair co-wrote six songs on Lavigne's coming album, Under My Skin: Slipped Away, Forgotten, Together, How Does It Feel, He Wasn't and Who Knows.

"She has instincts I had never seen before," Kreviazuk says of Lavigne, whose 2002 debut, Let Go, sold a whopping 14 million copies. "I learn from her because we think differently. I think with my head and she thinks with her gut."

Another difference is that Kreviazuk writes on piano and Lavigne on guitar. After writing for three weeks in Toronto, Kreviazuk -- then pregnant in her first trimester -- invited Lavigne to move into the Malibu home she shares with her husband, Raine Maida of Our Lady Peace.

At Kreviazuk and Maida's oasis up the Pacific coast from Los Angeles, Lavigne could head south into the big city to work with other people, then return to this homey environment, where the couple also has a recording studio.

There, Kreviazuk taught Lavigne some piano so that she could play the parts on stage.

"She wanted to learn," Kreviazuk says. "And I was like, 'You can.' She's really good at playing and singing, and a lot of people can't do that, and for her age, for someone who doesn't come from a schooled music background -- when she wants something, she goes after it."

Kreviazuk describes one of their collaborations, He Wasn't, as "a super-fun little punk throwaway, screw-you-to-boys song." Maida produced the track, along with four others on Under My Skin, one of which he co-wrote called Fall To Pieces.

Another of Kreviazuk's contributions is a dark, driving rock song called Forgotten, inspired by similarly vibed music Lavigne was consumed with at the time.

"She was kind of going through this goth, Marilyn Manson (phase), totally finding herself in really dark heavy music, and wanted to make sure that that side of herself came through on the album.

"I didn't want her to get stuck down with the female chick relationship," Kreviazuk says. "I wanted the things that we came up with to be really good.

"I wanted to do her right for this big follow-up record."