While her boyfriend was on tour in Canada with his band SUM 41, young Avril got flirty with one of his biggest rivals, DOUG ROBB from American rockers HOOBASTANK.
The grungy teen singer was performing at the World Music Awards on Wednesday and after a couple of sherries too many she found herself canoodling with Doug.
Sozzled Avril was in a celebratory mood after belting out her hits, which include Sk8er Boi and My Happy Ending, at the Las Vegas awards.
Even though she is only 19, two years too young to have a legal drink in the USA, a steady stream of booze was filtered through to her all night.
And it’s no wonder she got so hammered. She spent much of the night with the ultimate queen of hellraising, COURTNEY LOVE.
At one stage she even found herself in a cage with two leather-clad dancers before record label bosses dragged her out and told her off for making a spectacle of herself.
But soon after she hooked on to Hoobastank singer Doug and congratulated him on his performance.
An onlooker said: “Avril was absolutely blathered after the awards show. She had a drink in her hand almost all night and organisers were far from happy because she was too young to drink.
"She was manic ? running around the party and acting like a real rock ’n’ roll chick.
Doug from Hoobastank took a shine to her and they seemed to hit it off straight away.
They left together at about 2.30am and went back to The Venetian hotel where Avril was staying. I doubt Deryck will be too happy when he finds out.”
In fact Deryck, who used to date hotels heiress PARIS HILTON, will be furious to find out that his bride-to-be invited another bloke back to her hotel.
The couple are planning to walk up the aisle next summer and have been telling friends how blissfully happy they are.
Avril might blame her behaviour on the deadly beer goggles.
Or maybe she just realised Hoobastank are better than Sum 41.
This could get Complicated.
A WORD of warning to AVRIL. It may be very rock ’n’ roll to hang out with wild girls COURTNEY LOVE and ANNA NICOLE SMITH while showing off your new engagement ring.
But it’s also bad for your health. As well as getting you hammered, they’ve got you smoking, too.
Let’s hope Avril, who had a hit with Complicated, had some headache pills nearby next day.