(CNN) -- Wayne Rooney and Paul Scholes scored as Manchester United beat 10-man Queens Park Rangers 2-0 Sunday to strengthen their grip on the English Premier League title with six matches to play.
Victory left the defending champions eight points clear of local rivals Manchester City, who were beaten 1-0 at Arsenal in the late kickoff.
Arsenal's Spanish midfielder Mikel Arteta beat England goalkeeper Joe Hart with a superb shot three minutes from time to all but end City's hopes of a first league title since 1968.
Second-placed City's misery was complete when striker Mario Balotelli was sent off just before the final whistle for a second yellow card.
Manager Roberto Mancini had told Sky Sports that with United winning at home to QPR his side had to win to stay in the championship race.
"Today for us is like a final, otherwise eight points is too much," he told Sky Sports.
Interviewed after the defeat, Mancini admitted that with the points gap "it's very difficult but we will do our best."
He was also angered by Balotelli, who was lucky to stay on the pitch after a first-half tackle on Alex Song before being booked after tangling with Bacary Sagna.
"The first tackle was bad," said Mancini. "I defend Mario because he is a good guy but if he doesn't change in the future he could waste his talent. He can't continue to play like this."
Arsenal's deserved win after a game they dominated took them two points clear of north London rivals Tottenham Hotspur in the battle for third spot.
Earlier, United continued their recent superb run against strugglers QPR after being given the benefit of a dubious early decision.
The visitors were immediately on the back foot when Shaun Derry was shown a straight red card for a challenge on Ashley Young in conceding a penalty.
It looked a marginal decision with television replays indicating Young was offside, but Rooney thumped home the penalty for his 30th goal of the season and his 12th in 12 matches.
QPR boss Mark Hughes said the club would be appealing the decision -- the second in recent matches to favor United after Fulham's Danny Murphy was denied a clear penalty in his team's 1-0 defeat last month.
"These are massive decisions that affect people's livelihoods. Decisions are not being correctly made and they are affecting too many people," the former United striker told reporters.
"The referee was too quick to put his whistle to his mouth. The kid was still rolling around and he had already given a penalty. His assistant didn't have the opportunity to put his flag up."
United took control and in the second half the veteran Scholes duly grabbed his third goal since coming out of retirement as United made it 11 wins in 12 EPL matches.
QPR remained just above the relegation zone albeit on goal difference alone after the defeat.