Tabitha Tindell's winning goal (1-0) gave Häcken a surprisingly good starting position ahead of the return match north of London.
Häcken's task there was as easy as it was difficult: Keep a clean sheet again and a spot in the group stage would be secured for the club that had such successes in Europe last season. They reached the quarterfinals in the Champions League back then.
Arsenal created numerous chances in Gothenburg last week but couldn't get past Jennifer Falk. Coach Mak Lind then - and rightly so - praised his goalkeeper.
Jennifer Falk is totally magical, he said.
Couldn't stand up
Now neither Falk nor the rest of Häcken's defense could stand up. Lia Wälti's 1-0 was followed by another goal from Mariona Caldentey just before halftime.
Tindell got a golden opportunity to reduce the score and equalize overall, but the finish was too weak. Instead, Beth Mead elegantly scored 3-0 and Häcken ended up in a situation that couldn't be salvaged.
It would have taken two goals to force extra time.
In the end, Norwegian Frida Leonhardsen-Maanum increased the score to 4-0, just two minutes after coming on.
Tough match and sad result. They were clinical and I think we were a bit lazy in our own penalty area, says Häcken's Anna Anvegård to Aftonbladet.
National team star Stina Blackstenius started for Arsenal and had a goal disallowed for offside.
Rosa Kafaji, formerly of Häcken, got a short substitute appearance.
Who will Hammarby get?
Hammarby reached the club's first group stage in the Champions League on Wednesday evening. 2-0 away against Benfica in Lisbon meant advancement with 3-2 overall.
Norwegian newcomer Cathinka Tandberg decided the match for the reigning Swedish champions, with her 2-0 goal on Emelie-Marie Joramo's pass.
The draw awaits on Friday.
September 27 - group stage draw
Group stage:
Matchdays 8/9 and 16/17 October, 12/13 and 20/21 November, 11/12 and 17/18 December.
February 7 - quarterfinal and semifinal draw
Quarterfinals:
March 18/19 and 26/27
Semifinals:
April 19/20 and 26/27
Final:
May 23, 24 or 25 at Estádio José Alvalade, Lisbon.
