Lewandowski opened the scoring in the 20th minute and added Barcelona's third goal in the 66th to take his league-leading tally to 17 goals in his first season in Spain.

Ansu Fati doubled the lead in the 56th and Ferran Torres rounded off one of Barcelona's most comfortable victories of the campaign in the 70th.

Barcelona picked right up where they left off before last week's international break when they beat Real Madrid 2-1 in the league to deal what is looking like a decisive blow to their rivals' title defence.

Second-placed Madrid play Real Valladolid on Sunday.

Barcelona will try to beat Madrid again on Wednesday in the second leg of their Copa del Rey semi-final match. Barcelona won the first leg 1-0 in the capital.

Lewandowski got his first goal after receiving a headed pass by Ronald Araujo in the area when he knocked down a long free kick by Jordi Alba. Lewandowski's second goal came after Gavi won possession and played the striker clear.

"This is not over and we have to keep going," Barcelona coach Xavi Hernandez said. "It was a well-rounded night for us and for players who needed to boost their confidence."

Given the opponent and his team's commanding league lead, Xavi allowed himself to experiment with his lineup.

Little-used central defender Eric Garcia started in a new position for him as the team's holding midfielder, while regular starter Sergio Busquets stayed on the bench ahead of the "clasico."

Saturday's game was the debut of Argentine Sebastian Beccacece as Elche's fourth coach of the season.

The hosts looked like a team that has only won twice in 27 rounds. Elche finished the game 58 points behind Barcelona - 13 to 71 - and, more importantly, 14 points from safety.

They were without first-choice striker Lucas Boye, who served a one-game suspension.

Jose Luis Mendilibar had a winning debut as Sevilla's new coach as they beat Cadiz 2-0. Lucas Ocampos and Youssef En-Nesyri scored in the second half.

Mendilibar, 62, has coached several Spanish clubs, with his longest spells in charge of Eibar. He is Sevilla's third coach of the season after Jorge Sampaoli and Julen Lopetegui both were let go.

Athletic Bilbao's Oihan Sancet broke the news to the team's fans that he had agreed to a long contract extension following their 0-0 draw with Getafe.

He agreed to a new deal that will tie the 22-year-old midfielder to the Basque club through 2032. Sancet leads the team with eight goals this season.

Also, Cristhian Stuani converted an 88th-minute penalty to give Girona a 2-1 win over Espanyol, who are danger of falling into the relegation zone after four defeats in a row.

Australian Associated Press