Not only was Bates in a Major League uniform for the first time, but he started at first base and batted ninth in Monday night's opener of a three-game series against the Oakland Athletics.
Jeff Bailey, who had been called up from Triple-A last week to replace the injured Mike Lowell on the roster, was placed on the 15-day disabled list with a high sprain of his right ankle.
Mark Kotsay has also been having some recurring tightness in his right calf, which is why Bates got the start on his first day on the job.
"We have nobody else," quipped Red Sox manager Terry Francona. "I'm making light of it, but Kots is limping around, we're facing a lefty. That's why we got him here. We needed somebody to play tonight."
Bates -- a third-round pick in the 2006 First-Year Player Draft -- is the latest prospect to find his way to Fenway Park.
He started the season in Double-A before moving to Pawtucket on June 9. Bates tore it up at Portland, hitting .340 with seven homers and 39 RBIs. At Pawtucket, he hadn't quite found a groove, hitting .182 with two homers and seven RBIs.
"[Bates is a] good first baseman," Francona said. "Again, there's some pop in the bat. He's young -- he hasn't been in Triple-A that long. I think we feel like we need this roster spot for about a week. Rather than go make a move, I think we all kind of enjoy promoting from within. We've had good success doing it. I think it's healthy for the organization. Hopefully this kid will help us win a couple of games."
Bates, a right-handed hitter listed at 6-foot-2 and 232 pounds, was excited to have the chance.
"Whatever they want me to do, I'll be more than happy," said Bates. "I'm here to help the team in any way I can. You just try to get out there and play between the lines like you're a little kid playing -- the game doesn't change."
Lowell will be activated on July 17, so Bates is expected to stay with the Red Sox until the All-Star break.
Ian Browne is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.