Barcelona came from behind to crush Galatasaray 4-1 at Istanbul's RAMS Park on Tuesday, scoring three second-half goals to condemn the Turkish champions to their second consecutive UEFA Champions League defeat.
Galatasaray took the lead in the 28th minute when Aleksey Batrakov fired home a deflected effort following a move involving Rafael Leao.
The hosts thought they had doubled their advantage five minutes later when Barış Alper Yılmaz headed in from close range after Victor Osimhen's initial header, but the goal was ruled out for offside following a VAR review.
Barcelona equalized in the 43rd minute through Joao Cancelo, who found the far corner after receiving a pass from Dani Olmo, sending the teams into halftime level at 1-1.
The Spanish side took control shortly after the restart, with Fermin Lopez heading home Lamine Yamal's cross in the 50th minute.
Just three minutes later, Anthony Gordon extended Barcelona's lead with a finish from a tight angle after another assist from Yamal.
Karim Adeyemi completed the scoring in the 65th minute, capitalizing on a loose ball following a move involving Yamal and Gabriel Jesus.
Galatasaray goalkeeper Uğurcan Çakır had earlier denied Gordon in the 16th minute, but the hosts struggled to contain Barcelona's attacking pressure after the break.
The defeat leaves Okan Buruk's side without a point after two Champions League matches, following their opening 3-1 loss away to Sporting CP.
Barcelona, meanwhile, maintained their perfect start under Hansi Flick, moving to six points from two games.
Galatasaray will travel to France to face Lille on Oct. 21, while Barcelona will visit Paris Saint-Germain in their next European fixture.