Mohamed Salah pushed Liverpool 10 points clear in the Premier League with both goals in a victory over bottom side Watford.
The Egyptian has struck in back-to-back league games for the first time this season, and also helped the Reds progress in Europe in midweek.
Former Arsenal forward Gervinho grabbed the winner to condemn new Napoli boss Gennaro Gattuso to defeat, while current Gunners striker Pierre-Emerick Aubameyang was kept quiet in a chastening loss to Manchester City.
Mohamed Salah (Liverpool)
The Egypt forward produced two superb goals to give the Reds a 2-0 win against Watford at Anfield. With bottom of the table Watford proving tougher than expected opposition, Salah broke the deadlock in the 38th minute when he raced clear to curl a fine finish in the far corner.
He added the killer second with an audacious flicked effort from close range in the last minute as leaders Liverpool moved 10 points clear of second-placed Leicester.
Salah has now scored 84 goals in 126 appearances in all competitions for Liverpool.
He has scored eight Premier League goals against Watford, more than he has managed against any other team in the top five European leagues.
Alex Iwobi (Everton)
The Nigeria winger remains without a goal since September after being denied a late winner in the 1-1 draw at Manchester United. Everton's first-half opener via a Victor Lindelof own goal had been cancelled out by Mason Greenwood's second-half equaliser when Iwobi had his chance to become an Everton hero.
There were just moments left to play when the former Arsenal star unleashed a superb strike that brought a fine save from David de Gea. Iwobi has scored just twice since his close-season move from Arsenal.
Pierre-Emerick Aubameyang (Arsenal)
The Gabon striker drew a blank as Arsenal were completely outclassed in a dismal 3-0 defeat against Manchester City.
Aubameyang was largely anonymous and the Gunners were three goals down by half-time as champions City ran riot at the Emirates Stadium.
Although the 30-year-old has 13 goals this season, he has cooled off considerably since his red-hot start to the season with just five goals in his last 13 appearances.
With Aubameyang not at his best, Arsenal's struggles show no signs of ending and they now sit seven points adrift of the top four.
Gervinho (Parma)/Kalidou Koulibaly (Napoli)
Ivorian Gervinho, 32, struck the winner in the third minute of injury time for a 2-1 success which spoiled Napoli coach Gennaro Gattuso's debut game. It was the fourth league goal this season for the former Arsenal, Roma and Hebei China Fortune player. Napoli's Senegalese defender Kalidou Koulibaly had a nightmare game, losing control of the ball after four minutes to allow seventh-placed Parma to score. Koulibaly went off with a thigh injury just after, later tweeting: "I'm sorry. For the goal conceded, for the defeat and for the injury."
Musa Barrow (Atalanta)
Gambian forward Barrow, 21, came off the bench and provided the cross which pulled a goal back for Atalanta in a 2-1 defeat to Bologna just days after the Champions League newcomers sealed their place in the competition's last 16. The Bergamo side are sixth in the league.
Karl Toko Ekambi (Villarreal)
The Cameroon forward scored the winner in a surprise 2-1 victory for Villarreal away at high-flying Sevilla in La Liga.
Toko Ekambi sidefooted home for his sixth goal of the season after excellent work by Manu Trigueros to control in the box and tee up his team-mate.
Victory dents Sevilla's hopes of joining the title race and means Villarreal sit 13th in the table, now eight points clear of the bottom three.
Achraf Hakimi (Borussia Dortmund)
The Moroccan failed to score or assist in Dortmund's big 4-0 over Mainz, however it would be hard to argue it was his fault. Two Hakimi pinpoint crosses put goals on a platter for Nico Schulz and Jadon Sancho in either half, however poor finishing robbed the Real Madrid loanee of his sixth and seventh assists of the season.
Amine Harit (Schalke)
Schalke's attacking midfielder was at the centre of everything during the Royal Blues' win over Eintracht Frankfurt, causing constant problems for the visitors' defence. Not only did he provide the assist for Benito Raman's opener, but the Morocco international created the three-on-one break which led to the goal.
Newly-promoted Metz are struggling against being relegated straight back to Ligue 2 but they picked up a hugely valuable point at home to Marseille thanks to Senegalese forward Nguette, who scored just his second goal of the season in a 1-1 draw when he steered home Fabien Centonze's fizzing cross to give his team a surprise lead. The 25-year-old also won a penalty early in the second half that would have likely sealed a massive win, but Yohann Pele did brilliantly to push out Habib Diallo's spot-kick, allowing Nemanja Radonjic to level with 20 minutes remaining.
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