Atletico Madrid were held to a 1-1 draw at city rivals Rayo Vallecano in LaLiga on Sunday after Conor Gallagher cancelled out Isi Palazon's opener for the hosts.
Palazon put Rayo ahead in the 35th minute off a fine pass from Andrei Ratiu after a quick breakaway, with the goal initially disallowed for offside but awarded after a VAR review.
The visitors suffered a further setback when they lost defender Cesar Azpilicueta to injury.
Atletico coach Diego Simeone tried to bolster his side's attack after the break with the introduction of Antoine Griezmann and Angel Correa, and it paid off quickly.
Gallagher equalised four minutes after the break, following a Correa build-up and brilliant play from Alexander Sorloth for his second league goal of the season.
However, Atletico could not keep up the pace to find a winner, dropping two points at the Vallecas Stadium.
"It is a very difficult pitch to play on, we didn't start well, we were bad, we lacked everything and in the second half we changed our attitude," Atletico captain Koke told Movistar Plus.
"We're dropping points in games like this and we have to continue as we did in the second half. We even had chances to come back but it wasn't possible.
"Gallagher comes from a different league, at a different pace, and we need people like him who can run," the midfielder added on the former Chelsea player.
Atletico, who are fourth on 12 points, six behind leaders Barcelona, next play at Celta Vigo on Thursday before next Sunday's derby against Real Madrid.
Rayo Vallecano are ninth with eight points.