Barcelona was shocked by Shakhtar Donetsk and lost the opportunity to become the first team to advance to the Champions League knockout stages.
The solitary goal of the match was scored by Danylo Sikan, who looped a header in response to Giorgi Gocholeishvili’s cross.
Although Newerton believed he had added a late second, the teenager’s attempt was disqualified for offside.
Barcelona was forced to wait as they needed a point in Hamburg to go through Group H with two games remaining.
The visitors dominated possession, but they couldn’t break through the Ukrainian champs.
But if Xavi’s team wins their next game against Porto on November 28 and stays atop Group H with 10 points, they will advance to the knockout stages.
Shakhtar, third in Group H with six points, last defeated five-time Champions League winners Barcelona in 2008.
For the first time since losing to Roma in the round of 16 of the 2017–18 season, Marino Pusic’s club is aiming to advance to the next round.