SAN DIEGO -- It wasn't like Padres manager Bud Black had to twist the arm of general manager Jed Hoyer to get him to come around on prospect Anthony Rizzo, although he was surely a strong advocate for getting the first baseman promoted sooner than later.

"We started talking ... if we brought him up in Interleague Play and put [Brad] Hawpe at DH and then played Anthony at first base," said Hoyer of a conversation he had recently with Black.

"Buddy was like ... why not now?"

Instead of waiting until next week when the team heads to Minnesota for another round of Interleague Play, the Padres will add the 21-year-old Rizzo to their roster before Thursday's game against the Nationals at PETCO Park.

Rizzo will make his Major League debut, starting at first base, and, according to Black, will hit somewhere between fifth and eighth in the order.

It figures to be the first of many starts this season for Rizzo.

"We're not bringing this guy up to platoon," Hoyer said.

Rizzo, who was hitting .365 with 16 home runs and 63 RBIs with Triple-A Tucson, flew to San Diego on Wednesday morning to have his sore thumb and the bone bruise in his left hand examined by the team's medical staff.

The hand checked out fine, paving the way for Rizzo's debut.

Rizzo wasn't available to the media on Wednesday.

So why promote him now?

"He's a 21-year-old kid, and we wanted to get him some seasoning," Hoyer said, noting that Rizzo hadn't played above the Double-A level before this season. "This wasn't the time we expected. This is a guy we thought would help us in 2012."

Rizzo, one of four players acquired in the December deal that saw the Padres send All-Star first baseman Adrian Gonzalez to the Red Sox, hit .400 in April and .344 in May. Rizzo showed power and plate discipline while impressing Hoyer, the Tucson staff and myriad San Diego front-office staff who rolled through Tucson.

Hoyer resisted the urge to promote Rizzo when the team was scuffling offensively early in the season. The Padres have been shut out a Major League-leading 10 times in 2011.

Hoyer also wanted Rizzo to get more at-bats against left-handed pitching. He hit .324 in 37 at-bats against lefties in his time in Tucson.

"I didn't think it was fair to bring him up to fix a team that was struggling," Hoyer said. "I don't think he's the savior of the team."

Earlier this week, Hawpe moved from first base to the outfield, a presumptive move to get him re-acclimated to the position, and clear the way for Rizzo to arrive.

Now, Black said, all that's left is for Rizzo to go out and play.

"We want him to continue to play his game and be the player he was in Spring Training ... not to do more than anything he's done throughout his career," Black said. "... We think he's going to continue to swing the bat."

And for those fans who were calling for Rizzo during a 9-17 April?

"I think it's good for the fans," Hoyer said. "I like the fact that there's a buzz about him coming up."