Nope, it's not a dubious diet quick fix for some role or other, he just fell on his face.

The 26-year-old actor had to have his mouth wired shut after he accidentally slipped outside his home in Los Angeles over the weekend.

A source told E! News that the 17 Again star can't speak at the moment due to the injury and also sustained a large gash on his face that required more stitches during the late night accident. So he'll have a sexy face scar, bonus!

The heartthrob is expected to make a full recovery but has been forced to cancel his upcoming promotional tour for his new movie, aptly entitled That Awkward Moment, which is due to be released in January.

It was recently revealed that Zac, who sought treatment in rehab for alcohol and drug abuse earlier this year, is dating Lily Collins.

The pair sparked speculation they are dating after they were spotted holding hands last month, and pals believe the 24-year-old actress could help the Lucky One star keep his life on track.

A source (when you read the following, it's obviously her publicist) previously said: "Lily is the perfect girl for Zac to be dating right now. She's young, gorgeous and smart - but more than anything, she doesn't drink or use drugs. Zac knows if he wants to save his career and his life, he needs to stay sober and it's making his transition a lot easier to be dating someone like Lily."

And, there are certain perks for Lily as well...