Manchester United maintained their seven-point lead at the summit with a 4-0 demolition of struggling Wigan Athletic on Tuesday.
In an open game, Robin van Persie and Javier Hernandez both bagged braces at the DW Stadium, with the former taking his Premier League goal tally to 16 for the season.
Champions Manchester City, in second place on the table, kept the pressure on their neighbours by beating Stoke City 3-0 in a simultaneous fixture.
United started their tie promisingly, as Hernandez's shot from a tight angle drew a save from Ali Al Habsi four minutes in.
The Mexican had the ball in the net seven minutes later but his effort was correctly disallowed for offside.
Red Devils full-back Rafael tested Al Habsi on the half-hour mark, with the keeper dropping smartly to foil the long-range strike.
United, though, scored the opener in the 35th minute, as Hernandez pounced on the rebound after Al Habsi failed to adequately deal with a shot from Patrice Evra.
The visitors doubled their advantage just before the break, as Van Persie shook off the attention of Ivan Ramis before curling the ball into the far right corner from inside the area.
Wigan looked to have pulled one back in the 59th minute, but Arouna Kone's tap-in off a left-wing cross from Franco Di Santo was adjudged to be from an offside position.
A minute later, Hernandez bravely beat Habsi to an Ashley Young cross but was unable to keep his volley on target.
Hernandez, however, rifled in his second goal in the 63rd minute after a Van Persie free-kick hit the wall and fell kindly for his teammate.
Soon after Van Persie smartly fashioned space on the edge of the area before firing just over the bar.
The Latics almost reduced the deficit in the 83rd minute, as Jordi Gomez's curling free-kick kissed the outside of the post.
Van Persie concluded the rout with three minutes to go when he tapped in substitute Danny Welbeck's unselfish cross from close range.