D.C. United will likely lean heavily on Chris Pontius with Dwayne De Rosario done for the season. (Patrick Smith/GETTY IMAGES)

Dwayne who?

Make no mistake: D.C. United would much rather have Dwayne De Rosario on the field than watching from RFK Stadium’s mezzanine level Sunday evening against Chivas USA.

But in the two matches since the 2011 MLS most valuable player suffered a season-ending knee injury, United has managed a pair of critical victories.

Although both results came against weak opponents and included harrowing finishes, United found ways to succeed without him. And in the process, it strengthened its playoff outlook with five games remaining.

“There are a lot of people doubting us right now,” Coach Ben Olsen said Saturday. “I’m getting a little tired of hearing it. Our players are tried of hearing it. Hopefully we can prove some people wrong.”

Late last year, United found itself in a similar predicament when Chris Pontius, the club’s best performer over the course of the season, broke a leg. Starting defender Dejan Jakovic was also sidelined for a long period.

Pontius’s absence heaped a greater attacking burden on De Rosario, whose inspirational play wasn’t quite enough to gain a playoff spot. Additionally, the defense wasn’t the same without Jakovic.

This fall, Olsen and the players say they believe improved depth and mental toughness are making a notable difference.

“We’re tuned in until the end,” Pontius said. “Last year we would take a play off and something happens. We have stronger voices out there and we are staying focused.”

Secondary players have contributed. Reserve midfielder Lewis Neal was instrumental in both recent victories, coming off the bench to score the go-ahead goal against New England and starting in a deep position alongside mainstay Perry Kitchen in support of Branko Boskovic at Philadelphia.

“Look out on the field, you would think he is still in his twenties,” Kitchen, 20, said of Neal, 31. “He can still move well, he can cover a lot of ground and in that position, he is comfortable and able to move the ball side to side.”

Forward Maicon Santos hasn’t scored in four months and missed six weeks with a foot injury, but on Thursday, entered for Boskovic and contributed the long ball that led to Lionard Pajoy’s tiebreaking goal.

Without De Rosario serving as a foil, Pontius (team-best 11 goals) will continue to attract primary attention from defenders. He was quiet for much of the Philadelphia match, but on the goal sequence, he maintained balance in the box despite getting hit on the leg and crossed to Pajoy.

In an age when players worldwide fall at a feather’s touch — or no touch at all — Pontius remained upright.

“Watching on tape, I got hit a little bit more than I thought in the game,” he said. “I am stumbling. It looks awkward. But do you think I am getting that call in Philly? I don’t think I’m getting it.”

Falling on contact, regardless how severe, is “not something we want guys to do, but if you do get whacked in the box, sometimes it is advantageous to go down,” Olsen said. “I am glad [by staying on his feet] he got rewarded.”

Chivas USA has lost four in a row and is winless in eight straight (0-6-2). With 21 goals, the California-based club entered the weekend with the same total as San Jose’s Chris Wondolowski, the league’s top scorer. Chivas has scored multiple goals four times.

Defender James Riley, who has started every match, is serving a red card suspension and midfielder Oswaldo Minda (18 starts) is out on yellow card accumulation.

United must guard against overconfidence, though. Chivas is 4-5-5 on the road, and on Wednesday, was even at Columbus, an Eastern Conference playoff contender, until an 89th-minute goal by the Crew.