Levante's astonishing run of form continued in a thrilling victory, with Boateng's hat-trick added to by a brace from Enis Bardhi.
It's still been a brilliant season for double-winning Barcelona but manager Ernesto Valverde may well regret the decision to rest Lionel Messi this evening.
The Nou Camp giants were desperate to record an unbeaten season to make up for their Champions League disaster and they only had a home fixture against Real Sociedad left.
Barca were awarded a penalty following a foul on Sergio Busquets by Boateng and Luis Suarez easily blasted home straight down the middle with 20 minutes to go.
"I am angry", said Valverde.
The defeat meant that Barcelona who have already lifted the La Liga trophy will not not be going the season unbeaten in their domestic League.
Levante, which was dangerously close to the relegation zone less than two months ago, took a shock early lead against the double victor when 21-year-old striker Boateng pounced from close range in the ninth minute.
"The match has been determined by a insane 10 minutes at the start of the second half". "You have to acknowledge what they've achieved, although it's odd that we conceded five goals for how the season's gone". Mainly used as a substitute during his first season, he started to feature more regularly during his second.
Coutinho pulled one back with a long strike that took a deflection off a defender in the 38th, but Boateng struck again while Bardhi got his two goals to build what proved to be an insurmountable lead.
Coutinho converted again in the 64th minute.
"But this does not take away everything we have done otherwise this season - everything we have achieved in league, the run we managed across two seasons - but, it is a shame".
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