Rooney, 32, scored the opening goal against ex-Manchester United team-mate Tim Howard but was left bloodied after a clash of heads with Colorado defender Axel Sjoberg in stoppage time.
“Delighted to score my first goal for DC United,” Rooney tweeted after his team won for just the fourth time in 18 matches this season. Two of those victories have come since Rooney made his debut on July 14.
The striker, England’s all-time record goalscorer, said he required five stitches after breaking his nose in the collision with Sjoberg.
Rooney, who played for boyhood club Everton last season following his return from Old Trafford, signed a three-and-a-half year deal with DC United worth $13 million earlier this month.
DC remain 11 points beneath the playoff places with 16 matches remaining and several games in hand over the six teams currently in line for the postseason.
After Rooney’s opener, an angled shot between Howard’s legs, United conceded an 82nd-minute equalizer and appeared destined to again share the points before going ahead on an own-goal.
Coach Ben Olsen called it an important win, not only for the points but also for the confidence his side can take from a gritty performance.
“Psychologically, this is huge for our group,” Olsen said. “The other team scoring a late goal — which has been our Achilles heel all year — to turn that around and get a winner, I think psychologically this was a huge boost for the team right now.”
Rooney, Olsen said, provided much of that lift.
“I don’t think it’s the first time he’s bled in a game,” said Olsen, whose white shirt was streaked with blood after he embraced his star.
“He is a tough guy and I think that he will shake it off. But again, it shows you what this means to him right now. He is in the box, putting his face on the line, understanding that this is a big moment.” DM