The rocker and Hills hunk hit the preview event for SBE's new L.A. nightspot Industry and, onlookers report, the sparks appeared to be flying...
"Avril and Brody were cozying up in a banquette," one eyewitness said. "The two were dancing, singing, drinking and having a blast."
If they locked lips, none of our spies caught it, but they did stay until late into the night and left together in a group. "They definitely looked extremely friendly," the source said.
As E! News was the first to report, Lavigne and Jenner started seeing each other in early February.
Also out whoopin' it up were Hollywood's new Captain America, hunky Chris Evans, and Bryan Greenberg, star of HBO's new How to Make It in America.
We're told Ms. Lavigne congratulated Evans on snagging the superhero role, but he spent a good chunk of the evening with a mystery, model-looking brunette by his side.
In other romance news, Kim Kardashian and Reggie Bush have called it quits. Check out the suddenly solo E! reality starlet in our Single in South Beach photo gallery.