The result keeps Barca in contention for a top-eight finish in the league phase, which guarantees direct passage to the last 16.

The Catalans face FC Copenhagen at home in their final league phase game next week.

Barca got back to winning ways on a freezing night in Prague after Sunday's La Liga loss at San Sebastian ended a run of 11 successive victories.

Reigning Czech champions Slavia, returning from a winter break, had previously only managed three draws and two goals in the Champions League this season.

But they took the lead on 10 minutes as striker Vasil Kusej forced the ball across the goal line at the far post after Tomas Holes's glancing header from a corner.

Lopez pulled Barca level in the 34th minute following a pass from skipper Frenkie de Jong that found him unmarked in the box.

Lopez gave the Catalans the lead eight minutes later with a low shot that caught Slavia goalkeeper Jindrich Stanek unprepared.

But Slavia drew level just before half-time as Lewandowski deflected a corner into Joan Garcia's net.

Olmo spared Barca blushes as he blasted superbly into the top corner in the 63rd minute, three minutes after replacing Pedri.

And Lewandowski found the right net on 71 minutes when he slotted home from close range from a Marcus Rashford pass.

Hansi Flick was without the suspended Lamine Yamal and striker Ferran Torres due to a muscle injury.

The game started with a minute's silence for the victims of Sunday's train crash in Spain that left 43 dead.

Slavia were eliminated after a fourth loss in seven European outings left them third-bottom in the standings.