And Arsene Wenger has also been linked with a deal for Bordeaux forward Malcom.

The Gunners currently sit sixth in the Premier League, eight points behind Chelsea in the fourth and final Champions League berth. It's looking increasingly likely that they will have to emulate Man United and win the Europa League to earn a return to European football's top table.

It means Arsenal are going to have a lot of games to negotiate, starting with next month's round-of-32 tie against Ostersunds.

But can Arsenal register them for the Europa League?

Who can clubs register for the knockout rounds?

Clubs can add three new players to their squads.
- Only one player can have played in the group stage of the other competition to which the club is currently in (so a Europa League player can move up to the Champions League, and vice versa)
- Only one player can have played in just the qualifying rounds of either competition.
- A third addition cannot have played in Europe at all.

Who is not eligible?

Players who have:
- Played in the same competition for another club
- Player for another club that is currently in the same competition

NO: Pierre-Emerick Aubameyang

The rules around player eligibility can get somewhat confusing here, so to avoid getting bogged down in the intricacies of the regulations (43.02) let's put it simply: Borussia Dortmund and Arsenal are in the same competition.

- Pierre-Emerick Aubameyang played for Borussia Dortmund in the Champions League group stage
- Borussia Dortmund have dropped into the Europa League
- Arsenal are also in the Europa League
- Thus, even though Aubameyang has not played in the Europa League this season, he cannot play for Arsenal in it because Dortmund are now in the same European competition.

YES: Henrikh Mkhitaryan

Just like Aubameyang, Henrikh Mkhitaryan would move from a club playing in the Champions League to Arsenal in the Europa League.

However, as Man United are still in the Champions League, Mkhitaryan is thus free to play for Arsenal in the Europa League

Could Arsenal have registered BOTH Aubameyang and Mkhitaryan anyway if eligible?

No, as clubs can only name one player who has already played in the other European competition group stage. A famous example came in 2009 when Real Madrid signed both Lassana Diarra and Klaas-Jan Huntelaar -- they chose to leave out Huntelaar. In this instance, Arsenal would have had to make a choice.

YES: Malcom

His club, Bordeaux, were knocked out of the Europa League in the third qualifying round by Videoton FC. Although Malcom played both legs of the tie, he is eligible for Arsenal as a player who played in the qualifying rounds is eligible for one of the additional slots.