Robert Lewandowski scored a superb hat trick in his first Champions League outing for Barcelona as his new team began their European campaign with a 5-1 victory over Viktoria Plzen at Camp Nou on Wednesday.

After Franck Kessie put Barcelona in front in the 13th minute, Lewandowski took over. He scored twice before half-time, either side of a Jan Sykora goal that temporarily restored Plzen's hopes of getting something from the game.

Lewandowski completed his sixth Champions League hat trick midway through the second half before Ferran Torres put the final polish on the scoreline with an emphatic volley.

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Lewandowski's treble saw him break a tie with Karim Benzema to stand alone as the third highest scorer in Champions League history, with 89 goals. He also became the first player in the competition's history to score hat tricks for three different clubs. The Poland striker now has eight goals in five games for Barcelona since arriving from Bayern Munich in the summer.

Several of Barcelona's summer signings came to the fore in an eventful first half. Kessie got his first Champions League goal to begin the scoring with a close-range header after another new arrival Jules Kounde headed a corner into his path.

Lewandowski's first goal, in the 34th minute, was the pick of the bunch. After a run through the middle from Sergi Roberto, Lewandowski steadied himself on the edge of the box and side-footed into the corner of the net with trademark pinpoint accuracy.

He had an easier task in the third minute of first-half stoppage time. Ousmane Dembele did the bulk of the work, winning the ball back on the right wing before supplying a sumptuous cross that left Plzen's goalkeeper stranded and with Lewandowski the chance for a simple stooped header at the back post.

Before the scoreline got away from them, Plzen gave the hosts a couple of scares in the opening period. The Czech champions were awarded a penalty in the 24th minute only to have it overturned after VAR flagged that Jhon Mosquera's elbow had struck Barcelona defender Andreas Christensen in the face before the Plzen forward was brought down in front of goal.

Plzen got their goal in the 44th minute when Sykora headed in from a Vaclav Jemelka cross but Lewandowski soon made sure it would count for little.

After restoring Barca's two goal lead right before the interval, Lewandowski put the game out of reach with another perfectly-placed effort from just outside the box in the 67th minute. The man who set up that effort, Torres, then got a goal of his own with an unstoppable volley from Dembele's chipped ball over the defense.

Barcelona will next be in action in the Champions League when they visit Lewandowski's former club, Bayern Munich, next Tuesday. Plzen will meet Group C's final team, Inter Milan, on the same day.