London - Manchester United capitalised on a slip-up by Manchester City to open up a massive 15-point lead at the Premier League summit despite a laboured display in a 1-0 win at home to Reading on Saturday.
City's defeat at 10-man Everton handed United a chance to further increase their lead and they grasped the opportunity through a solitary first-half goal from Wayne Rooney at Old Trafford.
Rio Ferdinand celebrated his recall to the England squad by creating the goal in the 21st minute, boldly striding forward before slipping the ball to Rooney, who beat Stuart Taylor with a deflected shot.
In response, Hal Robson-Kanu grazed the post with a crisp 20-yard strike for second-bottom Reading, who sacked manager Brian McDermott on Monday.
Taylor saved from Robin van Persie and Ryan Giggs in a quiet second half, but although United were well below-par, their 20th English league title now seems only a matter of time.
Everton all but ended City's title defence earlier in the day with a gritty and controversial 2-0 win over the defending champions at Goodison Park.
The hosts won despite having Steven Pienaar sent off, while City should have had a late penalty at 1-0 down when referee Lee Probert awarded a free-kick despite Marouane Fellaini handling the ball inside the Everton box.
City assistant coach David Platt said manager Roberto Mancini was too "angry" to speak to media after the game and claimed his side had been denied a blatant spot-kick.
"You've just played it to me (on a television replay) and it's not even on the line of the area, it's three yards inside," he told Sky Sports.
"People can draw their own conclusions, but we didn't get it. Perhaps we could have got more out of the game if the decisions had gone for us."
Leon Osman made the breakthrough with a wickedly swerving strike in the 32nd minute, with Nikica Jelavic adding a second in injury time after Pienaar had been shown a second yellow card for a shin-high foul on Javi Garcia.
"We have had one or two dips but that was more like us today," said Everton manager David Moyes, whose side lost 3-0 at home to Wigan Athletic in the FA Cup last weekend.
"I thought we had a bad performance last week, which the fans rightly reminded us about, but we just reminded them they are supporting a really good team."
Victory temporarily lifted Everton into fifth place, but they slipped back to sixth after Arsenal won 2-0 at Swansea City to move to within two points of fourth-place Chelsea.
January signing Nacho Monreal and Gervinho struck late in the game at the Liberty Stadium as Arsene Wenger's side responded in positive fashion to their mid-week elimination from the Champions League.
"The spirit we showed today was fantastic. We're up for the battle," said Arsenal manager Wenger.
Meanwhile, Liverpool lost ground in the race for European qualification after losing 3-1 at Southampton.
Morgan Schneiderlin neatly converted a Jay Rodriguez knock-down in the sixth minute to put Southampton ahead at St Mary's, before Rickie Lambert doubled the hosts' lead with a deflected free-kick.
Philippe Coutinho replied for Liverpool on the stroke of half-time, but Rodriguez made sure of victory in the 80th minute as Mauricio Pochettino's side pulled seven points clear of the relegation places.
Queens Park Rangers were left seven points adrift of safety at the foot of the table after losing 3-2 to relegation rivals Aston Villa in a thrilling encounter at Villa Park.
After Jermaine Jenas gave QPR an early lead, Villa hit back through Gabriel Agbonlahor and Andreas Weimann, only for Andros Townsend's deflected strike to draw the visitors level in the 73rd minute.
However, there was a further twist in the tale, as Christian Benteke stroked home the winning goal from Weimann's cut-back with nine minutes remaining.
Benteke's goal allowed Villa to put six points between themselves and the bottom three, although third-bottom Wigan have two games in hand.
In the day's other game, Stoke City failed to reverse their disappointing recent form in a goalless draw at home to West Bromwich Albion.