Mariona Caldentey scored a stoppage-time penalty to secure victory for a wasteful Arsenal at home to Danish side HB Koge in the first game of their Women's Champions League campaign.

Arsenal, who had struggled in front of goal against a side made up of several part-time players, were heading towards a disappointing draw when Caldentey scored from the spot after Selina Cerci was tripped in the box.

The Gunners earlier thought they had scored when Chloe Kelly sent an outside-of-the-boot prod past Alberte Vingum, but her strike was ruled out after a VAR check deemed Stina Blackstenius to have been in an offside position and in the goalkeeper's eyeline.

But otherwise Arsenal looked toothless all too often, enjoying dominance of the ball but unable to find a way through.

The strength of the defensive performance from the visitors made a difference, too, with the energetic half-time celebrations of Koge boss Kristian Morch highlighting the determined nature of his side's display.

Arsenal lacked aggression in the final third and were often sloppy in possession, gifting opportunities for the Danish side to press and snatch the ball.

Gunners boss Renee Slegers had made eight changes from the side which salvaged a 1-1 draw with Manchester United at the weekend, but opted to switch things up at the break and introduce Alessia Russo in the place of Blackstenius in search of a goal threat.

But it provided little of the sort as the second half proceeded in the same manner as the first, with Arsenal dominating but struggling to fashion clear-cut chances.