Barcelona could not recover from an awful Marc-Andre ter Stegen mistake as they lost at Atletico Madrid.
Marc-Andre ter Stegen's extraordinary error gifted Atletico Madrid the decisive goal as they defeated Barcelona 1-0 at the Wanda Metropolitano.
Saturday's hard-fought contest was settled by a remarkable Yannick Carrasco strike in the third minute of first-half stoppage time, ending Atleti's 20-match winless run against Barca in LaLiga.
Ter Stegen – making just his third Blaugrana appearance in all competitions since returning from a knee injury – rashly set off in pursuit of the ball near the halfway line and was beaten by Carrasco, who kept his cool to find the net.
It was a setback Barca could not recover from as they succumbed to a third league defeat of the season to remain 10th, also losing Gerard Pique to a knee injury as Ronald Koeman's teething problems show no sign of easing.
The visitors had held their own in a lively start that saw Antoine Griezmann stab his volley just over before Ter Stegen dived away to his right to make a smart save from Saul Niguez's 20-yard drive.
Marcos Llorente came closest to an early breakthrough but blasted against the crossbar.
Jordi Alba interrupted a subsequent lull in proceedings with a sublime pass between Kieran Trippier's legs to send Lionel Messi through, yet he shot too close to Jan Oblak from a tight angle.
A nutmeg at the other end proved far more costly on the stroke of half-time, however, as Carrasco nudged the ball beyond Ter Stegen, who had inexplicably charged 40 yards from his goal to leave the Atletico winger with a straightforward finish into an empty net.