The Polish marksman scored the only goal of the match from a penalty in the 28th minute, cementing his position as the league's top scorer this season.
The 36-year-old leads the Spanish top flight's scoring chart, three strikes ahead of Real Madrid's Kylian Mbappe.
With a 1-0 win over Rayo Vallecano, Barcelona leapfrogged Atlético Madrid and Real Madrid to reclaim the top spot in the La Liga table, news outlets reported.
Lewandowski in November 2023 took home the Spanish premier league's Pichichi top scorer award for the 2022/2023 season.
The award was presented after the Pole ended his first season with Barcelona in June 2023, by winning the Spanish top flight's golden boot.
The Pole has now scored 91 goals for Barça in all competitions.
Lewandowski has previously won seven top scorer awards in the German Bundesliga, where he played for Borussia Dortmund and Bayern.
The Polish goal machine in October 2022 won the Gerd Müller Trophy for the best striker of the 2021/2022 season at the France Football Ballon d'Or Awards in Paris.
Meanwhile, Polish goalkeeper Wojciech Szczęsny made several crucial saves and kept a clean sheet in his next La Liga appearance for Barcelona on Monday, public broadcaster Polish Radio’s IAR news agency reported.
Szczęsny joined the Spanish giants in October last year.
(gs)
Source: IAR, PAP