Robert Lewandowski hit a second-half hat-trick to power Barcelona to an entertaining 4-2 win over 10-man Valencia on Monday in La Liga.

The champions' victory denies leaders Real Madrid the chance to take the crown by simply beating Cadiz next Saturday. Los Blancos are 11 points clear of Barcelona with five matches remaining.

Fermin Lopez sent the hosts ahead before Valencia striker Hugo Duro levelled and Pepelu netted from the spot to turn the game round.

Valencia goalkeeper Giorgi Mamardashvili was sent off late in the first half for handball and Lewandowski equalised soon after the break before adding another two late on.

It rained all day in drought-ridden Barcelona and the threat of a soaking left the Olympic Stadium half empty, with an attendance of 30,000.

The small crowd might also have been a response to last weekend's Clasico defeat, which laid out the red carpet for Real Madrid to whisk away Barcelona's title, as well as the detested Monday night slot.

La Liga rescheduled the game at only a week's notice, meaning many could no longer attend.

Those who were present enjoyed a surprisingly entertaining clash, with Barca coach Xavi Hernandez triumphant in his first match after deciding to stay in charge next season.

"I think the team did well... we lacked calmness, tranquility, but I'm satisfied with the team's attitude," Xavi told DAZN.

Visitors Valencia, eighth and striving for European football next season, carved out the best early chances.

Hugo Duro's flick from close range was saved by Marc-Andre ter Stegen. On-loan Real Madrid winger Peter Federico dragged a shot wide when barrelling through on goal.

Barcelona took the lead when Lopez headed home from Raphinha's whipped cross.

Valencia were quickly level after a grievous error by Barcelona goalkeeper Marc-Andre ter Stegen, who ran out of his box to try and intercept a long ball.

He got there first but botched his attempted dink over Duro's head and the striker controlled the ball and held off Ronald Araujo to roll home.

Key errors 

It soon got worse for Barcelona, with Araujo -- crucially sent off in the Champions League quarter-final defeat by Paris Saint-Germain -- foolishly giving away a penalty by felling Federico.  Valencia midfielder Pepelu fired the penalty down the middle to put Los Che ahead.

The game turned Barcelona's way shortly before the break when Valencia's goalkeeper erred.

Mamardashvili miscontrolled the ball on the edge of his box, giving it away to teenager Lamine Yamal.

As the youngster tried to round the goalkeeper, the Georgian touched the ball with his arm outside the area and, after a VAR review, was dismissed.

Replacement Jaume Domenech saved Raphinha's free-kick, but could not keep out Barcelona's equaliser, early in the second half.

Lewandowski headed home from a corner to start Barcelona's comeback.

The game lurched from end-to-end, with Domenech saving brilliantly from Araujo's header and Barca substitute Pedri making a last-ditch challenge to stop Diego Lopez from striking.

Eventually, Lewandowski nodded Barcelona back in front from close range when Araujo's header from a corner dropped into his path.

The Polish international wrapped up his treble in stoppage time with a well-placed free-kick, his 16th league goal of the season.

"The first half, we didn't have much space in attack, but most important is if you lose one or two goals, we can always score three or four," Lewandowski told DAZN.

"If we score a lot of goals, it's a lot easier for everyone."

Barcelona's victory took them two points ahead of neighbours Girona, third, whom they visit next Saturday.

The minnows are chasing Champions League qualification which they could secure with a victory, which could also hand Madrid the title.

"It'll be a great game, two teams looking to go on the attack," said Xavi, whose side lost 4-2 at home against Girona in December.

"It will be a great spectacle, as we saw in Montjuic."