Robin van Persie will miss Arsenal's Champions League round of 16, second leg clash with Barcelona on March 8, the club have confirmed.
Van Persie has been ruled out for at least three weeks after sustaining a knee injury in Sunday's Carling Cup final defeat by Birmingham.
However, Arsene Wenger described Cesc Fabregas as a "possible" for the Nou Camp trip after revealing he is making quick progress in his rehabilitation from a hamstring problem.
Losing Van Persie is a seismic blow to Arsenal's hopes of staging another upset against the Spanish champions. The in-form 27-year-old Holland striker sustained the injury in the act of scoring Arsenal's equaliser during the 2-1 defeat at Wembley.
The goal was his 13th in 11 games - a haul that includes the equaliser against Barcelona in the first leg, which the Gunners edged 2-1.
"Unfortunately, we had bad news on the scan and he will be out for the next three weeks for sure," Wenger told Arsenal TV Online.
"It could be longer. The shortest delay we can imagine is three weeks, so he is definitely out for Barcelona."
The loss of Van Persie has been slightly tempered by the encouraging update on Fabregas' fitness. The Spain midfielder sustained his hamstring problem against Stoke last Wednesday but has responded well to treatment.
He will definitely miss Wednesday's FA Cup fifth-round replay against Leyton Orient and Saturday's Barclays Premier League showdown with Sunderland, but could return for Barcelona.
"Cesc is looking possible [for that game]. He is making quick and good progress. It is possible," said Wenger.