BARCELONA, SEPTEMBER 7

Robert Lewandowski scored a hat-trick in his first Champions League game for Barcelona to power the Catalans to an emphatic 5-1 home win over Viktoria Plzen on Wednesday.

Midfielder Franck Kessie put Barca in front in the 13th minute, heading in his first goal for the club following a corner.

Lewandowski extended their lead with a right-footed finish into the bottom corner in the 37th, after Barca had survived a scare which almost led to them conceding a penalty and having a man sent off.

Viktoria were awarded a penalty and Barca defender Andreas Christensen was shown a red card for hauling down Jhon Mosquera but a VAR review showed Mosquera had struck Christensen with an elbow and the decision was overturned, the Plzen forward being shown a yellow card instead.

Plzen pulled themselves back into the game in the 44th minute with a header from Jan Sykora but Barca quickly restored their two-goal cushion when Lewandowski produced a diving header from an Ousmane Dembele cross in first-half stoppage time.

The Poland striker completed his treble midway through the second period, meeting a layoff from Ferran Torres and curling the ball inside the far post with one touch.

"That's how Robert is, insatiable," said coach Xavi Hernandez of the striker Barca paid Bayern Munich 45 million euros for in a big summer of spending in a bid to return the club to past glories.

"The way he trains, the way he helps the team, his humility, his work-rate...I can't praise him enough because it's not just about his hat-trick, it's the way he works, how he knows to dominate the tempo of the game," Xavi added.

It was Lewandowski's sixth hat-trick in the Champions League and he became the first player in the competition's history to score one for three different clubs, having netted trebles for Bayern and Borussia Dortmund.

Torres completed a hugely satisfying evening for Xavi Hernandez's side by scoring the fifth goal to put Barca top of Group C. They head to Bayern next on Sept. 13, when Plzen host Inter Milan.

It was a near-perfect night for Barca and in stark contrast to their first game of the competition last season, when they were outclassed and beaten 3-0 by Bayern on their way to crashing out at the group stage for the first time in 21 years.

"It was a complete game, we dominated them," added Xavi.

"They defended well, they man-marked us but Dembele was brilliant and Lewandowski made the difference. We were the superior team and I'm delighted with the players who came off the bench as well as those who started. Everyone was really up for it."