Sir Alex was delighted to see his side beat Everton and keep yet another clean sheet, but the United boss insisted there is still room for improvement.

The Reds went five points clear at the top of the league but the 1-0 scoreline made for some nervy moments as the final whistle approached.

“You only need a second to lose a goal,” Sir Alex told MUTV. “And in a situation like today, where Everton kept going and kept playing balls up to the edge of the box, that can happen.

“The aim of football is to kill teams when you’ve got them by the throat and we had Everton by the throat several times and didn’t do that.

“Everton were very energetic and athletic and because we didn’t score a second goal – even though we created some terrific openings – they were always going to carry on and keep fighting. They took us right to the wire.”

In the end, Cristiano Ronaldo’s penalty separated the sides.

“He’s taken his penalty well,” Sir Alex said. “He was under pressure, it was right before half-time… but he remained calm.”

Ronny perhaps should have been given another chance from the spot when Michael Carrick was brought down by Joleon Lescott after the interval. The Reds’ boss certainly thought so.

“That was a clear penalty,” he said. “There’s no question about that. But you’re never going to get two penalties…

“Michael Carrick did well today. His penetrative runs were very good. We’ve spoken about our midfielders making those sort of runs into the box and Michael did that well today.”

Cristiano Ronaldo declared himself satisfied after scoring the winner against Everton – but insists all that matters is that the team keep winning.

Following his brace at West Brom on Tuesday, the winger netted his 14th goal of the season from the penalty spot on Saturday to send the Reds five points clear at the top.

"I am happy with my season, but the most important thing is the team," Ronaldo told MUTV."We are top, the lads are playing very well, I’ve scored a few important goals and want to carry on doing my job to help the team.

"It was very tough today. Everton had a good game at the weekend against Liverpool and we knew it was going to be difficult.

"But we played well, especially in the first half when we created a few chances and managed to score the goal. The second half was a little more difficult, with Everton just playing on the counter-attack."

Ronaldo was not too disappointed that United failed to add to his opener and credited Everton's resilience.

"If we win every game 1-0 it’s good!" he continued. "Sometimes it’s important to score goals but Everton are a difficult team to play against. We have to appreciate the attitude and character of the team."

Ronaldo also reserved praise for Edwin van der Sar, who kept his 12th consecutive league clean sheet to break a 30-year-old English league record.

Ronaldo said: "It’s unbelievable! Edwin deserves it because he is a great goalkeeper and a great man who works a lot for his age! I’m really happy not just for him but for all the lads, especially the defenders who support him a lot."

Third-placed Liverpool host second-placed Chelsea on Sunday when both sides will be fighting tooth and nail to claw the ground back on United.

"It’ll be a tough game," Ronaldo added. "Maybe a draw is the best result, but one or both of them will definitely drop points!"

Michael Carrick echoed his manager’s comments after United squeezed past Everton at Old Trafford on Saturday.

The Reds won 1-0 courtesy of a Cristiano Ronaldo penalty – won by Carrick – but the former Spurs midfielder would have preferred the margin to have been greater.

“We played very well in the first half-hour but Everton made it difficult for us,” he told Setanta Sports. “Everton have proved how good a side they are in recent weeks so we’re happy to come away with the win.

“You’re not always going to get games where everything goes right and you play great football. We’re happy with 1-0 – it’s another clean sheet and we looked solid as a team.

“We had chances to score a few more... there’s still more to come from us.”

Carrick was at the centre of two penalty claims – one given, the other waved away by referee Mark Halsey.

“There was definitely contact for the first one,” he said. “The player [Mikel Arteta] clipped my ankles and my momentum carried me over. I don’t think Everton can have any arguments about that one. I thought the second one was a penalty as well. I’ve nicked the ball and he’s [Joleon Lescott] come across me as I’m running through. But you get some decisions and you don’t get others. I’m not worried complaining too much.”

The midfielder was delighted with the three points, and just as pleased to be part of the team’s 12th consecutive league clean sheet.

“It’s a huge achievement and shows how well we’ve been playing and also the character we have to stick together when it’s not going so well. We’re very satisfied with that.”

Van der Sar: Equal to the few efforts that threatened him setting a new English record of clean sheets 6

Neville: The double pronged attack of Baines and Pienaar caused him so many problems and never looked himself 4

Ferdinand: Tested more than at West Brom and never looked in serious trouble 7

Vidic: The Serbian rock launched himself into any danger that Everton conjured up 8

O’Shea: Uncomplicated and steady effort kept the Reds defence intact yet again 6

Ronaldo: First half he had a number of crowd pleasing moments but faded in the second 7

Fletcher: Recent inactivity seemed to have affected his impact. Never fully got to grips in midfield 5

Carrick: Penetrating drives, nicked tackles, blocked shots, won a penalty and should have won two - brilliant 9

Park: Energy levels high as usual but apart from one shot not a lot came from his effort 6

Tevez: The all action hero was at it again. When Rooney is back for West Ham he’d be unlucky not to start against his old club 8

Berbatov: Not much came off for the Bulgarian. Ran into a few brick walls 5

Subs:

Brown (sub Neville 56) Full blooded effort 6

Giggs (sub Fletcher 74) Calming influence 6

Not used: Fabio, Welbeck, Gibson, Eckersley, Kuszczak

Everton: Howard, Hibbert, Baines, Lescott, Jagielka, Arteta, Cahill, Neville, Pienaar, Osman, Fellaini (Anichebe 68)

Goals:

United: Ronaldo 44 pen)

Everton: None

Bookings:

United: None

Everton: None

Battle of the Bosses:

David Moyes' disciplined outfit tested the Reds but Fergie kept faith with his usual blueprint

Referee: Mark Halsey - Spotted one penalty and missed one 5

Attendance:75,399