Given its long injury list and daunting domestic and international schedule, D.C. United lacks sufficient troops to battle on two fronts.

After a 2-0 home loss to Costa Rica's Saprissa Wednesday night, one front - that of reaching the MLS playoffs - will be plenty to handle. Saprissa outshot D.C. 17-10, and got goals from Walter Centeno and Jairo Arrieta on either side of halftime as both teams opened the group phase of the Concacaf Champions League.

The Costa Ricans took command early and breezed past D.C., which left Jaime Moreno on the bench and brought on Fred for Luciano Emilio at halftime. Craig Thompson, Boyzzz Khumalo and Ryan Cordeiro also got starting assignments and seldom matched the class and cohesion of Saprissa, which fielded several Costa Rican internationals and played some very polished soccer.

United contributed to its own demise when Devon McTavish waded into a midfield tussle that prompted referee Marco Rodriguez to call a foul on Santino Quaranta. McTavish barreled in and kicked the ball as well as Alexander Robinson, apparently after Rodriguez had blown the whistle, prompting the official to send him off and caution Quaranta as well in the 35th minute.

United had just fallen behind, 1-0. Saprissa marked its domination of the opening 32 minutes when McTavish poked the ball away from Alejandro Alpizar as the Costa Rican fell, but while lying on the ground Alpizar laid it off to Centeno, who rolled it low into the far corner past keeper Zach Wells, who started in place of recent arrival Louis Crayton.

Down to 10 men, United seldom threatened the Saprissa goal as its efforts to establish momentum ran aground in midfield through turnovers and poor decisions. It had threatened only once playing 11-v-11 when Cordeiro's ball down the flank released Clyde Simms, whose cross dropped for Thompson at the far post. the rookie dawdled on the ball and when his shot was deflected, Emilio failed to control it and couldn't get a shot off.

Wells saved from Michael Barrantes before halftime, during which United clearly failed to regroup. Its jittery defensive play resulted in a second goal when Arrieta pounced on a weak clearance and blasted a spectacular shot from 25 yards for a 2-0 lead.

Still, United battled on when it could keep possession for more than a few seconds. A mazy run by Fred resulted in a free kick near the penalty area that Marc Burch sent screaming on frame. Saprissa goalie Keilor Navas nimbly deflected it away for his first save of the match.

Burch continued to test Navas as the minutes ticked by. A cross to Simms produced a safe catch by the keeper, and another blistering free kick from nearly 30 yards yielded a flashy flying parry.

For its late thrusts, United probably deserved a goal. Yet a clearly superior Saprissa comfortably captured three points, and United has just a few days to prepare for another tough test: a long cross-country trip to play the Galaxy at Home Depot Center on Saturday.