David Phillip, Associated Press
Boston Red Sox's David Ortiz, left, and Kevin Youkilis laugh during baseball practice at Coors Field in Denver on Friday. Boston is scheduled to play the Colorado Rockies in Game 3 of the World Series in Denver on Saturday.

DENVER — The Boston Red Sox have three corner infielders and only two corners to put them in.

With no designated hitter for the World Series games in Colorado, Red Sox manager Terry Francona plans to use slugger David Ortiz at first base. That means Kevin Youkilis, who's batting .396 in the postseason, is out of the starting lineup for Game 3 instead of playing first or moving to his original position and displacing Mike Lowell at third.

"You're talking about a guy that drove in 120 — two guys that drove in 120. And we love Youkilis as a hitter, too," Francona said after workouts at Coors Field on Friday. "It's a difficult situation to be in. ... I'd just rather play all three of them."

Boston holds a 2-0 lead in the best-of-seven series, but Saturday night's game presents Francona with the same problem all AL managers face when they go to the NL park. In fact, the difficulty for Boston is as pleasant as a problem can be: All three of the candidates have been playing well since the playoffs began.

"It's hard to get one of your guys out of the lineup," Ortiz said before taking grounders at first base. "But you've got to do something."

Ortiz made 27 appearances at first base over the last three years, mostly in interleague play. In the 2004 World Series, he brought his mitt to St. Louis and made a heads-up throw to trap a runner drifting off third base.

"I've played first base before and it wasn't that bad," Ortiz said. "It's just not Gold Glove-caliber."

Francona also said his plan is to move Dustin Pedroia into Youkilis' No. 2 spot in the batting order and switch center fielder Jacoby Ellsbury from ninth to Pedroia's slot leading off. Ortiz might play all three potential games in Denver, but Francona said Friday he hasn't ruled out a different configuration for Game 4, or 5 if necessary.

"I think David is a really good hitter, and I think Mikey Lowell is a really good hitter, and I actually think Youk is a really good hitter," Francona said. "But they won't let us play all three of them. So we'll go with this."

Ortiz batted .332 with 35 homers and 117 RBIs this season, but he played just seven games at first base when the Red Sox visited NL parks in interleague play. He hasn't made an error this year.

Ortiz has also been playing most of the year with a partially torn meniscus in his right knee, an injury that required a cortisone shot over the final weekend of the regular season. Ortiz said the knee is fine, especially considering he might only need to play two more games; Francona said he'll keep an eye on how his big DH — make that former DH — is moving.

"The worry I have — some of it is physical — but some of it is just the fact that he hasn't been out there," Francona said. "And even if you're a really good Gold Glove-caliber player, when you're not out there every day, it's not fair.

"But he's done it in the past, and he's handled it in the past."

One time Ortiz handled it well was when the Red Sox went to St. Louis for Game 3 of the 2004 Series. Ortiz started at first base for both games at Busch Stadium and Doug Mientkiewicz relieved him both times to shore up the defense and protect Boston's lead.

But that just meant sitting Kevin Millar, who batted .238 in that postseason; this year, playing Big Papi means sitting either Lowell or Youkilis, each a key part of the offense that has outscored opponents 45-7 over the last five postseason games.

Lowell drove in 120 runs to lead the Red Sox in the regular season and is batting .333 in the postseason while averaging an RBI per game. Youkilis ended his nine-game hitting streak in Game 2, but he's still batting almost .400 with four homers and 10 RBIs since the start of the playoffs.

"Having to play National League (rules) takes one of their big boppers out of the lineup," Rockies pitcher LaTroy Hawkins said. "It definitely helps. The whole dynamic of the game has to change."

Still, if it were just about the offense it would be an easy decision.

Merely indispensable in the regular season, Ortiz becomes otherworldly in October. He is batting .385 in 12 postseason games this year, and with 13 walks to go with his 15 hits he has gotten on base more often than not.

So it's no surprise that Francona wants to keep him in the lineup.

But Ortiz is a risk in the infield — an experiment Francona would rather not make in the season's most important games.

"Anything around me, it's going to be (caught)," Ortiz said. "After that, I don't know."

Youkilis has handled 1,586 straight errorless chances at first base in the regular season, breaking Stuffy McInnis' club record for first baseman. At third, Lowell is the all-time major league leader with a .976 fielding percentage.

Francona said he would go with offense for now, and keep Youkilis handy as a defensive replacement if Boston takes a lead.

"We're here to try to win a World Series. You can't be upset," Youkilis said. "We're up two games to none. ... You should move on and go to another team if you're worried about your playing time and think you need to play over somebody else. This is the World Series. You've just got to be happy to go out and help in any capacity you can."