Arsenal will be without Leah Williamson on Thursday as they look to turn around their Champions League qualifier against Hacken and reach the group stage.
Having featured off the bench when the Gunners were beaten 1-0 in last Wednesday's first leg in Sweden, Williamson was then absent due to concussion protocol on Sunday as Jonas Eidevall's side opened their Women's Super League campaign with a 2-2 draw against Manchester City at the Emirates Stadium.
Eidevall confirmed in his press conference ahead of Thursday's contest at Meadow Park that the England captain was again unavailable, and added: "I don't have (a timeframe) at the moment, sorry.
"It's guided by our medical team and when I have something more concrete to communicate, I will do that.
"(She picked up the injury in) training. I'm not going into more specifics than that. It was an incident in training and it's only been one incident."
After being led by Eidevall to the Champions League semi-finals in 2022-23, Arsenal missed out on the group stage last season as they were knocked out in the qualifying rounds by Paris FC.
Asked if it would be a failure to not win on Thursday, Eidevall said: "If we don't qualify, yes. I would consider that. Our ambition is to go into the group stage and that's what we need to do."
He added: "I'm very positive and optimistic about our chances this season. We're going into the game with really high motivation tomorrow night, and we're going to do everything in our power that we can do to overturn it."
City look set to secure a return to the group stage for the first time since 2021, having been eliminated in qualifiers two years in a row and then fallen short of a European berth when they came fourth in the WSL in 2022-23.
Gareth Taylor's side, WSL runners-up last season, lead Paris FC 5-0 heading into their second leg at Joie Stadium.
Taylor said: "They won 6-0 at the weekend away from home (against Guingamp). Our mentality has to be 0-0, and we have to go and earn the right.
"We did that last week really, really well. We need to be ready tomorrow for a team that has pretty much got nothing to lose."
Taylor also revealed that midfielder Jill Roord, who has been recovering from an anterior cruciate ligament injury, is set to be available to make her return to the matchday squad for Sunday's home league clash with Brighton.
Thursday will also see Celtic look to seal a place in the group stage for the first time when they play Ukrainian side Vorskla Poltava in Airdrie, leading 1-0 from the first leg.
