Mat Ryan has become Arsenal's second addition in the January transfer window, joining on loan from Brighton for the remainder of the campaign.
The Australian international goalkeeper fills a void left by Matt Macey's exit, after he joined Scottish side Hibernian permanently, but creates an issue within the squad.
Premier League regulations state a club cannot have more than 17 non-homegrown players in the squad, with Ryan's addition seeing Arsenal hit that quota.
There may be some confusion for fans checking the Premier League squad lists as Macey's middle name, coincidentally, is Ryan - which shows 'Matthew Ryan' appearing on the list.
However, those lists have not been updated yet, with Sead Kolasinac still included but now on loan with Schalke.
Eliminating Kolasinac from the current list, Arsenal move down to 16 non-homegrown players but the signing of Ryan takes the Gunners back to the maximum amount.
That highlights an issue with the loan signing of Martin Odegaard from Real Madrid to go ahead, while Mikel Arteta is still in the market for a left-back.
Exits are now likely to occur in the final days of the window to trim Arsenal's squad of further non-homegrown players, with a number of potential candidates.
Runar Alex Runarsson, signed in the summer, has been linked with an exit on loan, while Shkodran Mustafi, out of contract in the summer, has also caught attention.
Both will have to leave the club in the final days of the window if Odegaard was to be followed by another non-homegrown player.
