Fernando Torres gave the visitors a fifth-minute lead, only for Wayne Rooney to equalise in controversial fashion, tucking home the rebound from a penalty given for a Javier Mascherano foul on Antonio Valencia which had started outside the area.

In a second half of few clear-cut chances, Park Ji-sung headed home the winner after an hour when he came through a crowd of bodies to finish Fletcher's superb cross.

The Scotland international hailed the character of Sir Alex Ferguson's men, who are chasing a record fourth successive championship.

"It was a difficult game, with not much football played," Fletcher told Sky Sports 1.

"You want to win the title with flowing football, but sometimes you have to grind out results and show character - that is what we did."

Fletcher maintained referee Howard Webb was right to give a penalty.

"I definitely thought it was a foul," said the United midfielder.

"He was pulling Valencia and the contact with his legs was right on the edge of the box.

"The keeper saved it, but Wazza (Rooney) is so composed that he was able to tap it in afterwards."

United returned to the top of the table, ahead of Arsenal by two points, with Chelsea, who still have a match in hand, set to face Blackburn this afternoon.

"The team which puts the most consistent run together will probably be champions, and we are making a good fist of it," Fletcher added.

United boss Ferguson insisted Mascherano should have been sent off.

He told Sky Sports News: "I thought the penalty kick decision was a red card, because I do not see how anyone could have stopped Valencia from shooting.

"That is a goalscoring opportunity as far as I am concerned."

Ferguson continued: "It was very tight and Liverpool are good at stopping you playing, we know that because that is your strength.

"But you have got to be patient and we scored a tremendous goal from Park Ji-sung, who played another vital role for us today."

Ferguson accepted the match had not been a classic.

"I am sure it wasn't, but it was so intense and you could not take your eyes off it - there was no-one watching on television who went for a cup of tea, that is for sure," he said.

Torres missed a late chance to snatch a point for Liverpool.

Ferguson said: "Torres has maybe tried to burst the ball, but that was the only break we got in the game really.

"Vidic was magnificent today.

"We have a very experienced back four, a very experienced goalkeeper and that gives us a real outstanding chance, albeit with seven difficult matches - but we have all got difficult matches, so what does it matter?

"It could very well go to the wire, if you look at the run-ins for the teams."

Liverpool manager Rafael Benitez felt there was not much between the two sides.

"It was very tight, they did not have too many chances, and neither did we," he said.

"With two top sides, it is always the little things which are the difference, and they were the better in these.

"After the goal, I always said it is about how you can control the game, and we could not, as we conceded early.

"In the second half, you could see Manchester United are a good team, but they did not have too many options and with a bit of luck, it could have been a draw."

On the penalty incident, Benitez did not feel his player had merited a red card.

"I have not seen the replay, but talking to people who have said it was inside and was a penalty, but Jamie Carragher was also there, so it was only a yellow card," the Spaniard said.

Liverpool are now well behind in the battle for fourth place, but Benitez insisted the battle goes on.

"It will be difficult, but we still have to fight," he said.

"There are still a lot of points to play for, so we have to keep going and see what happens in the next game.

"The supporters can see the team was solid again, we played three games this week and have scored goals.

"You can see we can win against anyone. You have to improve when you play against a top side, but we created chances.

"We now have to take it one game at a time, and it (fourth place) will also depend on what the others do."