With 10 goals in December alone, Luis Suarez has propelled Liverpool up the English Premier League and enhanced the team's title credentials with each game.
Another double from the Uruguay striker on Saturday clinched a 3-1 victory over Cardiff that took Liverpool to the top of the standings, for now, having finished seventh last season.
"We can't ever think we have cracked it. We can't become complacent, you have to be focused and move on to the next game," Liverpool manager Brendan Rodgers said. "We are very calm. We are not getting carried away. We are focusing on improving our performance level."
Manchester City is just a point behind after winning 4-2 at Fulham, despite throwing away a two-goal lead in heavy wind and rain at Craven Cottage.
Liverpool and City could be overtaken by Arsenal if the London club wins the derby against fourth-place Chelsea on Monday.
Manchester United remains outside of the top four in seventh place despite the champions beating West Ham 3-1 to make it two wins out of two after losing the previous two league games.
Newcastle remains two points ahead of United after winning 3-0 at Crystal Palace. In the day's other games, Stoke rose to 10th by beating Aston Villa 2-1, bottom-placed Sunderland drew 0-0 with Norwich, and managerless West Bromwich Albion was held to 1-1 by Hull.
Hull was the last team to beat Liverpool, on Dec. 1, but a fourth straight win since that setback was produced in style.
10 goals in 4 games
In those four games, the Reds have scored 17 goals — 10 provided by Suarez — and conceded just three.
The latest double from the striker came a day after signing a new contract through 2018, having been denied a transfer to Arsenal in the summer transfer window.
There's certainly been no lingering, obvious bitterness at that snub. His tally for the season is a league-leading 19 despite missing the first five games while banned for biting.
Suarez's first against Cardiff came after 25 minutes, racing onto Jordan Henderson's cross and then volleying past goalkeeper David Marshall.
Suarez turned provider in the 42nd, latching onto Henderson's throughball before squaring for Raheem Sterling to slot home.
Henderson returned the favour on the stroke of halftime, backheeling to Suarez, who curled in the shot through a packed penalty area.
It was job done for Liverpool, with Cardiff's goal after the break — Jordon Mutch's 58th minute-header — proving to be just a consolation.
The result further weakened Malky Mackay's job as Cardiff manager. Mackay's position has come under fresh doubt this week after Malaysian owner Vincent Tan sent him an email requesting him to stand down or be sacked.
"I won't be walking away," Mackay responded on Saturday.
It was a better day for another Scottish manager as David Moyes' side won a fourth straight game in all competitions.
The three points were wrapped up before halftime against West Ham, with Danny Welbeck driving in his first goal at Old Trafford in 14 months.
And Welbeck exchanged passes with Adnan Januzaj before the 18-year-old midfielder stepped past James Collins and scored his first ever home goal for United.
On a mixed afternoon, Januzaj's blatant dive by the touchline drew a booking.
"He's elusive the way he moves and it can bring defenders into tackles," Moyes said of Januzaj.
United took until the 72nd to score again, with substitute Ashley Young's goal from Wayne Rooney's layoff ensuring Carlton Cole's late strike for West Ham provided little concern.
Neighbour City, though, left it late to secure the win at Fulham.
Yaya Toure put City in front with his fourth goal from a free kick this season and captain Vincent Kompany fired in City's second just before halftime.
But five minutes after the break City conceded possession near the Fulham penalty area, and Kieran Richardson completed a rapid counterattack to begin the hosts' fightback.
Fulham was gifted an equalizer in the 69th when Kompany inexplicably sliced the ball past his own goalkeeper Joe Hart, who was recalled after being dropped in league games since October.
But Jesus Navas restored City's lead in the 78th when he slotted through goalkeeper Maarten Stekelenburg's legs, and James Milner wrapped up the win five minutes later.