The summer transfer window has been open for quite a while in England and it closes on 9 August - just before the new season kicks off.
Signing Fellaini is something Gunners fans likely wouldn't approve of, but on a free transfer, there's no real risk involved with the deal.
The new Arsenal gaffer apparently tried to lure the 30-year-old to PSG when he was in charge of the French club, and now he's set for another go, believing that Fellaini has the muscular mindset that the notoriously soft Arsenal midfield lack.
Manchester United have tried to convince him to sign a new deal with manager Jose Mourinho also quite vocal about securing his services before the World Cup. While there is nothing that Mourinho can do to stop Fellaini from joining whoever he wants to, he may finally put pressure on the board to offer the midfielder a greater incentive to stay at the club.
Fellaini has been selected in Belgium's World Cup squad and the Red Devils had hoped he would sign his extension before he travelled to Russian Federation for the World Cup.
The big Belgian defensive midfielder has always been linked with a move from Old Trafford this summer but the smart money had him heading to Roma or AC Milan. This suggests a move could happen sooner rather than later.