Steven Gerrard scored twice from the penalty spot as Liverpool stretched its Premier League winning streak to nine matches and returned to the top of the table with a 2-1 win at West Ham on Sunday, while Arsenal was dealt another blow by a top-five team in a 3-0 thrashing by Everton.
For once, the free-scoring Reds had to battle hard to claim a hard-fought victory ahead of their much-anticipated clash against Manchester City in a meeting between the two main title contenders.
"It is going to be a magnificent atmosphere at Anfield," Liverpool manager Brendan Rodgers said. "The supporters really urged us on today and we want to see if we can get 10 in a row."
With five games remaining, Liverpool leads Chelsea by two points as it pursues a first league title since 1990. Manchester City is four points off the pace but has two games in hand.
Earlier, Everton made Arsenal pay for their poor defending with strikes from Steven Naismith and Romelu Lukaku as well as an own goal from Mikel Arteta.
"You could say there was a lack of fight," Arsenal manager Arsene Wenger said. "It's a massive worry. We have to come back with much more personality and much stronger challenges."
Arsenal has secured only two points from its last four matches as the Gunners remain in fourth place in the standings, but only one point above Everton, which has a match in hand and a better goal difference.
Gerrard put Liverpool ahead in the 44th minute after West Ham defender James Tomkins handled a flick by Luis Suarez in the area. But West Ham defender Guy Demel equalized on the stroke of halftime when Liverpool goalkeeper Simon Mignolet spilled a cross following a challenge from former Liverpool striker Andy Carroll.
The assistant referee initially signalled for a foul on Carroll, but referee Anthony Taylor overruled him despite protests from the Liverpool players.
Gerrard then scored his second in the 71st minute after Liverpool defender Jon Flanagan was brought down by West Ham goalkeeper Adrian.
Arsenal manager Arsene Wenger criticized his players for their poor display and admitted his side is now facing an uphill task.
"I'm 100 per cent determined to fight to make the top four but it will be difficult," said Wenger. "We have a run-in that is feasible but we must focus on the quality of our displays before dreaming of places."
While Everton continued its superb attacking form to cut its deficit to the Gunners to one point in the battle for the fourth place, Arsenal stuttered again against a strong team. The Gunners have lost all their away league matches against the current top five, also losing 6-3 at Manchester City, 5-1 at Liverpool and 6-0 at Chelsea.
Everton, which has scored 12 goals in its last four games, claimed a sixth consecutive league win.
"It would mean everything," Naismith said about his team's possible top-four finish. "But we have believed from the start of the season and we have shown that in these recent performances."
The defeat piled pressure on Wenger, who is chasing a first trophy with the Gunners since 2005 and has guided them to Champions League football in each of his 16 full seasons in charge. Everton had beaten Arsenal just once in their last 15 league meetings but looked the superior team on Sunday.
Naismith opened the scoring in the 14th minute from inside the box after Leighton Baines picked Lukaku with a low ball. The Belgium international forced Wojciech Szczesny into a save but the Arsenal keeper could not hold the ball and Naismith fired home the rebound.
Arsenal's defence buckled again with Lukaku hardly challenged when he doubled the Merseyside team's lead in the 34th minute following a good collective move. The powerful forward collected a through ball from Kevin Mirallas then cut inside and fired a low shot past Szczesny.
Wenger's team improved after the interval, but Everton decided the game when Bacary Sagna lost the ball to allow Mirallas to launch a quick counterattack. The Belgian slipped the ball to Naismith who could not round Szczesny but the loose ball came into Mirallas' path before rebounding into the net following a challenge from Arteta.