With Arsenal well behind leaders Manchester City in the race for the Premier League and out of the FA Cup, the Carabao Cup and Europa League provide the best chances of silverware for Arsene Wenger's side in 2017-18.
Arsenal will face City in the Carabao Cup final on February 25 at Wembley, and resume their Europa League campaign against Swedish side Ostersund on February 15 with the second leg taking place at the Emirates exactly a week later.
Alexis Sanchez played once for the Gunners in the Europa League, scoring in the 3-1 win against Koln, but has been traded to Manchester United for Henrikh Mkhitaryan, leaving an open spot in Arsenal's 25 man European squad.
Pierre-Emerick Aubameyang is set to move to the Premier League before the end of the transfer window, having played for Borussia Dortmund in the Champions League, scoring four goals in six group games.
Mkhitaryan also featured for United in the same competition, but is eligible for inclusion in Wenger's squad for the resumption of the Europa League. However, Dortmund's failure to get out of a group containing Tottenham and Real Madrid means they now drop to the Europa League, ruling Aubameyang out of Arsenal's European campaign.
UEFA rule 43.01 states that "For all matches from the start of the round of 32, a club may register a maximum of three new eligible players for the remaining matches in the current competition. Such registration must be completed by 1 February 2018 (24.00CET) at the latest. This deadline cannot be extended."
The next point in the rulebook goes on to discuss which players are eligible and which are not, with Mkhitaryan able to play due to the fact that he has not already played in the Europa League and that the club he represented in Europe are also not in the same competition as his new club.
Aubameyang meets the first requirement, but is ineligible because of the second. Borrusia Dortmund are now in the Europa League and could possibly meet Arsenal in the knockout stages. Due to this rule, Wenger cannot choose him in his 25-man squad as he is cup-tied for both Champions League and Europa League for the remainder of 2017-18.
Arsenal's other winter signing, Kostas Mavropanos is eligible for inclusion as his former club PAS Giannina did not play in Europe this season. With Theo Walcott leaving the club, Wenger will have another spot to fill ahead of Thursday's squad deadline and the Greek defender may be included.