Gallagher signed from Chelsea on Wednesday in a deal worth around £33m and came on as a second-half substitute in Sunday’s victory.

His side already led 2-0 by the time he was introduced, with Antoine Griezmann having opened with a first-half free-kick before Marcos Llorente doubled the lead with a spectacular second-half strike.

Gallagher’s arrival was marked earlier this week by thousands of Atletico fans attending his unveiling, with the 24-year-old entering the pitch to a light show and pitchside flamethrowers.

His role was a primarily muted one given the state of the game, but he slotted in well alongside the rest of the Atletico midfield and linked play to help his side try to work through Girona.

Atletico – who drew 2-2 with Villarreal in their opening La Liga game last weekend – were infuriated on Sunday when Girona goalkeeper Paulo Gazzaniga escaped a red card in the first half despite handling the ball outside his area.

But their spirits were soon lifted when Griezmann, taking aim from the edge of the area, expertly curled an effort inside of the far post from the resulting set piece.

Full-back Llorente later charged down the right-hand side before rocketing a strike over the head of Gazzaniga from distance.

Koke rounded off the victory in the fourth minute of added time by slotting home a Llorente pass from close range.

Gallagher could be handed his first start at his new club when they take on Espanyol on Wednesday.