BOSTON –– Two losses in as many nights to the first-place Tampa Bay Rays may make it unlikely that the Red Sox will repeat as American League East champions. But with just 17 games remaining and the Red Sox holding a commanding five-game lead in the wild card race heading into yesterday’s action, a fourth playoff appearance in the last five years seems a virtual guarantee.

The Sox are getting healthier, with J.D. Drew, David Aardsma and Bartolo Colon set to return to the lineup any day now, and Sean Casey and Mike Lowell already returned from DL stints.

Of course, plenty can change over the final 2½ weeks, but the club is already mulling its 25-man playoff roster.

The Sox will probably again go with a smaller pitching staff for the first round, which has a maximum of five games.

Particularly if the Sox end up as the American League wild card entry, the Sox could afford to carry just 10 pitchers. They would face the A.L. West champion Los Angeles Angels of Anaheim. Should the Angels finish with the best record in the league, they would have the option –– as the Sox did a year ago –– of playing their five games over the course of eight days.

In such a scenario, the Sox could use just three starters in five games, with their top two pitchers ( Josh Beckett and Jon Lester) set up to pitch twice on normal (four days) rest.

A look at the possible makeup for the ALDS:

CATCHERS (3): Jason Varitek, Kevin Cash and David Ross. Varitek and Cash are the obvious choices, but Ross stands a good chance of being included –– at least in the first round –– to give manager Terry Francona more options.

Over the course of the regular season, Francona has refused to pinch-hit for the slumping Varitek. But in the playoffs, where every at-bat becomes magnified, sentiment goes out the window. The presence of Ross would allow Francona to, say, pinch-hit for Varitek in the seventh, then do the same with Cash in the ninth inning or later and still have a third catcher.

INFIELDERS and DH (7): Mike Lowell, Alex Cora, Jed Lowrie, Dustin Pedroia, David Ortiz, Kevin Youkilis and Sean Casey.

Lowell, Lowrie, Pedroia, Youkilis and Ortiz are the obvious starters, with Casey and Cora in reserve.

Casey is a accomplished left-handed bat off the bench and Cora can play all four infield positions capably.

OUTFIELDERS (5): Jason Bay, Coco Crisp, Jacoby Ellsbury, J.D. Drew, Mark Kotsay.

Bay and Drew, assuming he’s healthy, are starters, with Crisp and Ellsbury options in center and Kotsay available to play all three outfield spots.

One drawback to the makeup of position players is the lack of extra right-handed hitters. On a given night, beyond the catching corps, the Sox will probably have three left-handed hitters on the bench (Cora, Casey, Kotsay) and either the switch-hitting Crisp or the left-handed hitting Ellsbury.

That won’t give Francona many options against left-handed pitchers. It’s possible that Jeff Bailey could squeeze into the picture, but that would probably mean going with just two catchers since it’s difficult to imagine him edging out any of the other reserves.

STARTERS (5): Josh Beckett, Jon Lester, Daisuke Matsuzaka, Tim Wakefield and Paul Byrd.

Wakefield and Byrd are starters in name only, since in a five-game series, there will be no need to go beyond the front three. They can work in long relief and give the Sox, in essence, a seven-man bullpen.

BULLPEN (5): Justin Masterson, Hideki Okajima, Manny Delcarmen, Javier Lopez and Jonathan Papelbon.

The five relievers are all obvious choices and provide a decent left-right balance. If Aardsma proves himself healthy in the next two weeks, he could be added if the Sox advance past the ALDS. For now, the Sox don’t need to carry a middle reliever, since that workload can be handled by either Wakefield or Byrd, neither of whom will get a start in the first round.

Masterson has clearly earned Francona’s confidence and will share the setup duties with Delcarmen and Okajima, depending on matchups.

smcadam@projo.com