Chelsea preserved their six-point advantage at the Premier League summit by beating Tottenham Hotspur 3-0 on Wednesday, while Manchester City kept pace with a 4-1 success at Sunderland.
Southampton's last-gasp 1-0 loss at Arsenal left defending champions City with a four-point cushion in second place, and the ease of the leading pair's victories suggests the gap is only likely to increase.
Chelsea had been held to a goalless draw at Sunderland at the weekend, but they returned to winning ways against Tottenham, who have not won at Stamford Bridge since February 1990.
Chelsea were missing top scorer Diego Costa due to suspension, but after Spurs striker Harry Kane had rattled the crossbar with an early header, the hosts went ahead in the 19th minute.
Eden Hazard picked the ball up wide on the left, swapped passes with Costa's replacement, Didier Drogba, and beat visiting goalkeeper Hugo Lloris at his near post with a powerful left-foot shot.
It was a disappointing moment for the France goalkeeper, and there was more frustration to come three minutes later.
Lloris fluffed a goal-kick straight to Hazard, who in turn fed Oscar, and the Brazilian teed up Drogba to fire home.
Loic Remy replaced Drogba in the second half and he found the target in the 73rd minute to complete a straightforward evening for Jose Mourinho's side.
Manuel Pellegrini's City had lost 1-0 on their previous four visits to Sunderland, but they ended the sequence thanks in no small part to a brace from in-form striker Sergio Aguero.
Captain Vincent Kompany's hamstring injury and Eliaquim Mangala's suspension saw City line up with Dedryck Boyata and Martin Demichelis at centre-back, and they fell behind in the 19th minute when Connor Wickham got ahead of Pablo Zabaleta to score.
But Aguero equalised two minutes later, effortlessly slipping past a defender and crashing home a ferocious shot from just inside the box.
Aguero's astute lay-off allowed Stevan Jovetic to make it 2-1 in the 39th minute and after Samir Nasri had teed up Zabaleta to chip Costel Pantilimon 10 minutes into the second half, Aguero claimed his second.
The Argentina international neatly converted James Milner's cross in the 71st minute to register his 14th goal of the season and confirm his status as the league's most dangerous player.
Arsenal closed to within two points of fourth-place Manchester United after Alexis Sanchez's 89th-minute goal snatched a 1-0 win at home to third-place Southampton.
Visiting goalkeeper Fraser Forster twice saved superbly from Danny Welbeck and produced a fine stop to repel substitute Olivier Giroud's header, only for Sanchez to tap in Aaron Ramsey's drilled cross at the death.
Southampton, beaten 3-0 by City on Sunday, are now just a point above United ahead of Monday's meeting between the sides at St Mary's.
In the day's other game, Sone Aluko cancelled out Romelu Lukaku's first-half opener to earn struggling Hull City a 1-1 draw at Everton.