Spurs' Australian boss Postecoglou, fighting for his own survival at the club too, may feel the stars are again aligning against him at just the wrong time again as the team's injury woes, so disruptive all season, have multiplied with just a week to go before the all-English showdown in Bilbao.
Kulusevski suffered the injury in Sunday's 2-0 loss at home to Crystal Palace after being caught by a challenge from Marc Guehi and had to come off in the 19th minute.
Postecoglou had hoped the Swedish playmaker would be okay but after scans, he underwent an operation on Wednesday.
"It will put him out for at least a few months," reported Postecoglou on Thursday.
"Yeah, gutted for Deki. Disappointing news. Initially we thought it wasn't too serious. The medical team were worried structurally about how the knee was but it blew up the day after and we knew there was an issue there.
"I have only got basic information at the moment in terms of recovery, but it will certainly put him out for a while."
The Kulusevski blow follows those of key midfield duo James Maddison, who suffered a knee injury in the 3-1 Europa League semi-final win over Bodo/Glimt on May 1, and Lucas Bergvall, who endured ankle ligament damage in training before that match.
The absence of that trio could be calamitous, leaving Spurs without their two principal creative playmakers and their go-forward Swedish central midfielder Bergvall as they seek to end their 17-year trophy drought.
Kulusevski has been a stand-out player at the Tottenham Hotspur Stadium ever since signing at the start of last season, with his 10 goals and 11 assists in 50 appearances in the latest campaign one of the bright spots amid Spurs' plight.
Meanwhile, Manchester United's equally beleaguered coach Ruben Amorim - his side are 16th, one place above Spurs - put on a brave face on Wednesday about his own 'must-win' final, saying there's no chances he'll be leaving United any time soon.
"I have a clear idea what to do. I understand the problems of the team, so I'm far from quitting," said Amorim, who's certain to oversee the worst ever points total and the lowest league finish by any United side in the Premier League era but could still get them to the Champions League, the prize for the Europa League champs.
"What I'm saying is that we need to perform and, we have this season, and in the future we need to perform or else they will change us.
"It is going to be really bad (if we don't get to the Champions League). I don't want to use that as an excuse.
"It is going to be really tough, and the patience of the fans and you guys (in the media) next year if we don't win it is going to be on the limit and we have to be perfect to continue with everything. I know that, so it's not going to be better in that way."
With agencies
