D.C. United's first competitive occasion of preseason — and that's a stretch, given the young opponent, mass substitutions and low-key nature — turned into something a bit more eventful than anticipated Saturday morning. Captain Wayne Rooney was supposed to play 45 minutes but left after 18 because of a shin injury, later deemed minor by the English superstar and his mildly concerned coach. Two days after he thought he was joining Paris Saint-Germain, Argentine playmaker Luciano Acosta accompanied the team to Joe DiMaggio Sports Complex but did not play — a moment of pause for a player who didn't return from France until late Friday night. Meanwhile, two rookies made good first impressions, Argentina's Lucas Rodriguez and Leonardo Jara made their debuts and United claimed a 1-0 victory over second-division Bethlehem Steel at Joe DiMaggio Sports Complex. Rooney, the centerpiece of United's renaissance last season, was injured in the 10th minute on a sliding collision with the goalkeeper. He received treatment on the field and on the sideline, re-entered the match four minutes later but then removed himself. For the rest of the afternoon, he sat on the bench with his right leg elevated and his lower shin wrapped in ice. "I've got a few of them before," said Rooney, 33, the all-time leading scorer for Manchester United and the English national team. "It took longer than I thought to ease down, so no point in taking any chances. I'm not too concerned." He said he hopes to play Thursday against FC Cincinnati in Bradenton, Fla.