Arsenal were dealt a major blow during the first half of their Carabao Cup semi-final second leg against Newcastle after Gabriel Martinelli was forced off with an injury.
Martinelli went down clutching his hamstring in the 37th minute at St James' Park.
Arsenal boss Mikel Arteta immediately signalled for teenager Ethan Nwaneri to come on following the blow.
Martinelli was seen limping off the field and the Brazilian is now set for a spell on the sidelines.
The loss of Martinelli will be another blow to Arteta amid a series of injuries in attacking positions.
Arsenal are already without Bukayo Saka and Gabriel Jesus, with the latter having been ruled out for the season with an ACL injury.
Arteta had admitted ahead of the match that he had been disappointed by Arsenal's January transfer window, acknowledging their failure to strengthen in attack.
A number of players were pursued, including Ollie Watkins and Alvaro Morata, but the Gunners failed to bring in reinforcements.
Arteta said: 'We had a clear intention which is a window open to explore the opportunities to improve our squad with players that can impact it.
'We haven't achieved it so we are disappointed in that sense, but as well we are very aware that we only want to bring certain kind of players and we have to be very disciplined with that as well and I think that we will.
'When you try your best and you do things with the right process and you see the people that we all share the same intentions and wills and after you don't achieve it, for sure there are things to learn from it, there always are, but you have to move on and that's a piece that was important in the moment and now we have to move on.
'Nobody knows whether it is better to have done it or not. We'll know probably at the end of the season.'
When pushed further on the topic of signing a striker, he said: 'It was a very similar narrative as well at the end of last season and it's been for a while, which I understand.
'But there are certain things that we can do, certain things that we cannot do and that's it. When somebody is showing that will to win to say, 'OK now is the moment to do it and we are willing to do it' then you cannot do it, OK you can be disappointed but at least you tried your best.'
Arsenal were beaten 2-0 on the night and 4-0 on aggregate by Newcastle, who will meet either Tottenham or Liverpool in the Carabao Cup final at Wembley on March 16.