A hat-trick from former Chelsea forward Pernille Harder condemned Arsenal to a 5-2 defeat at Bayern Munich on their return to the Champions League group stage.

Arsenal, who were eliminated in last year's qualifying round by Paris FC, had successfully navigated fixtures against Rangers, Rosenborg, and a two-legged tie with Hacken to secure their place in Group C. However, they were unable to claim any points from their opening match.

Jonas Eidevall’s Gunners took the lead in Munich through Mariona Caldentey after 30 minutes. Despite Laia Codina making it 2-2 in the 56th minute, Harder ended her European goal drought for Bayern with three goals in the final 17 minutes, securing an emphatic victory for the hosts.

Arsenal had been frustrated by a goalless draw against Everton in the Women’s Super League on Sunday, but welcomed back Leah Williamson and Stina Blackstenius to the starting line-up.

It was Bayern’s England international Georgia Stanway who posed the first threat with a long-range strike, comfortably saved by Manuela Zinsberger. Arsenal then squandered a chance to take the lead when Katie McCabe’s superb left-footed free-kick found Codina, whose tame effort was easily gathered by Maria Luisa Grohs in the 14th minute.

The visitors continued to press for the opening goal and were rewarded half an hour into the match. McCabe was once again instrumental, delivering a cross from the left which Caldentey volleyed into the bottom corner to put Arsenal in front.

Bayern responded immediately and after Zinsberger denied Giulia Gwinn, the hosts drew level two minutes before half-time. Stanway delivered a superb cross, which captain Glódís Viggósdóttir headed home.

The German side maintained their momentum after the break, taking the lead in the 56th minute when Klara Bühl played in Sydney Lohmann, who rifled her shot in at the near post.

Arsenal quickly replied as Codina headed in McCabe’s corner nine minutes later. However, after Eidevall substituted McCabe, the Gunners collapsed in the final 20 minutes of the match.

Harder, who had failed to score in her six Champions League appearances for Bayern last season, broke that streak in the 73rd minute, heading in from a Carolin Simon corner.

Just five minutes later, Harder added a second, finishing from Bühl’s cross to make it 4-2. She completed her hat-trick with four minutes remaining, following up on Zinsberger’s save from her initial effort and poking home the rebound from Gwinn’s delivery.

Harder's late heroics sealed a dismal night for Arsenal, leaving them without points in their Group C opener.