It is now certain.

Hart High graduate Trevor Bauer will start Thursday for the Arizona Diamondbacks at Atlanta in his Major League debut.

The 21-year-old and 2008 Hart High grad was the third overall pick in last year’s First-Year Player Draft.

“He’s excited, we’re excited to have him, let’s be honest,” Diamondbacks manager Kirk Gibson told MLB.com. “It’s a great challenge for Trevor, and he’s up to it.”

Bauer is 11-1 with a 2.23 ERA in 16 starts between Double- and Triple-A this season.

The game starts at 4:10 p.m.