Boston's Daisuke Matsuzaka works out Wednesday at Fenway Park in Boston.

Boston ? Daisuke Matsuzaka will be on the mound for the Red Sox when the AL championship series begins Friday night against the Tampa Bay Rays.

That doesn’t make him Boston’s ace.

Josh Beckett is still No. 1 in the Red Sox rotation – especially during the playoffs – even though he had the worst outing of the three Boston starters who faced the Los Angeles Angels in the first round. Beckett, coming off a strained side muscle, is scheduled to pitch Game 2 in the best-of-seven series against the Rays.

“Before Beckett’s last start, he was the best postseason pitcher maybe in the history of the game,” Red Sox manager Terry Francona said Wednesday after announcing his rotation. “He had the audacity to be a little rusty after two weeks. We don’t need to run away from Beckett, we need to get him on a run.”

Francona chose Matsuzaka to start against the Rays in Game 1 not because of Beckett’s injury, and certainly not because the team lost any faith in a guy who won five straight postseason outings before Boston’s Game 3 loss to the Angels. Even with his off night versus L.A., Beckett is 6-2 with a 2.09 earned-run average in his postseason career.

Instead, Francona said, the Red Sox scheduled Beckett for the second game because it would give him, Matsuzaka and Game 3 starter Jon Lester essentially the same amount of rest. Tim Wakefield will start Game 4, with Matsuzaka, Beckett and Lester ready to pitch again in Games 5-7 if necessary.

“Nobody’s going to throw three,” Francona said. “So having those three twice is really what’s important, regardless of how it’s lined up.”

Matsuzaka was 18-3 with a 2.90 ERA this season, best among the Boston starters in both categories. But he also led the rotation with 94 walks, raising his pitch count and limiting him to 1672â3 innings.

“We’re going to have to wait him out and see how he’s throwing,” Rays rookie Evan Longoria said. “It’s a little bit different when you’re playing in a playoff game. Walks are so important, and if he’s going to come out and do what he normally does, he usually walks a ton of guys and throws a lot of pitches early. If we can get him on the ropes early, we’ve really got to take advantage of that.”