Ousmane Dembele scored and laid on a hat-trick of assists as Barcelona ripped apart Athletic Bilbao in a 4-0 win in La Liga on Sunday to stay three points behind leaders Real Madrid.

The French winger was at his thrilling best after being brought back into the side and challenged to make a difference by his coach Xavi Hernandez, ruining former Barca manager Ernesto Valverde's return to Camp Nou.

Dembele netted the opener and then created goals for Sergi Roberto and Robert Lewandowski in the first half as Barcelona danced around Athletic.

Ferran Torres fired home in the second half after Dembele found him in the area to complete the drubbing.

"It's the life wingers have, ups and downs; they have to go for it; it's what I always say," said Xavi. "Some days it works, others not, but they have to go for it. Ousmane made the difference."

It was Valverde's first game facing Barcelona since being sacked in January 2020 after winning two league titles, but it did not go to plan for him.

"It's been a horrible day because we lost 4-0," said the coach. "They punished us today."

Elsewhere, Premier League leaders Arsenal dropped points for the second time this season in a frustrating 1-1 draw at Southampton. Meanwhile, Newcastle climbed to fourth place after punishing Hugo Lloris' mistakes in a 2-1 win at Tottenham.

Arsenal looked set to move four points clear at the top of the table when Granit Xhaka continued his fine form by smashing home the opening goal at St. Mary's after just 11 minutes.

Mikel Arteta's side dominated the first half but failed to add to their advantage, with Gabriel Jesus guilty of missing big chances on either side of the break.

Arsenal were punished when Stuart Armstrong produced a composed finish to level 25 minutes from time.

Martin Odegaard smashed home as the league leaders pushed for a winner, but the goal was ruled out as the ball had already gone out of play prior to Kieran Tierney's cross.

A draw leaves Arsenal just two points clear of Manchester City at the top of the table.

Newcastle's strong start to the season gained further momentum as they inflicted Tottenham's first home defeat since April.

Eddie Howe's side climbed into the Champions League places, two points behind third-placed Tottenham, after extending their unbeaten run to seven matches.

In Italy, Victor Osimhen extended Napoli's lead at the top of Serie A to three points with the only goal in a hard-fought 1-0 win at Roma, their 11th on the bounce in all competitions.

Nigeria forward Osimhen crashed in his third goal in as many games in all competitions with 10 minutes remaining of his first start since early September to hand Napoli a win at one of their fiercest rivals.

Luciano Spalletti's side took advantage of Atalanta's 2-0 home defeat to Lazio earlier on Sunday to move further ahead of the pack and become the only unbeaten side left in Italy's top flight.

Napoli's nearest challengers are now reigning champions AC Milan following their 4-1 thumping of Monza on Saturday.

Roma are seven points back in fifth after a dogged, battling performance at the Stadio Olimpico, which lacked in invention but largely kept a lid on possibly Europe's most exciting team.

"I think we did enough to merit a draw tonight," said coach Jose Mourinho.