The Gunners were eliminated from the Europa League on Thursday night after Arsenal suffered a 2-1 aggregate loss to Spanish side Atletico Madrid.
Arsene Wenger’s side were unable to capitalise on home advantage against 10-man Atletico in the first leg after Antoine Griezmann cancelled out Alexandre Lacazette’s opener.
Arsenal lost 1-0 to los Rojiblancos in the second leg of their last-four clash after former Chelsea FC striker Diego Costa netted on the stroke of half-time.
The Gunners are in sixth place in the Premier League table and Arsenal won’t finish in the Champions League qualification spots.
Arsene Wenger’s side still aren’t assured of a sixth-placed finish ahead of the visit of Burnley at The Emirates on Sunday afternoon.
The Frenchman is set to stand down as manager at the end of the season to leave the Gunners contemplating a new era at the Emirates Stadium.
Former Manchester United captain Keane warned the next Arsenal manager about the size of the task awaiting him.
“He [Wenger] should be proud of his achievements, obviously, but there is no quick fix at Arsenal,” Keane told ITV Sport.
“They need to get the right manager in, they need funds, new players and new characters. They are so far behind Man City it’s untrue.
“Way behind United, Liverpool, Spurs and Chelsea. Some tough days ahead at Arsenal. For all the problems we have mentioned, I still think it is a great opportunity for a top manager to come in and fix things, but it won’t happen quickly.”
Arsenal are set to finish outside the top four in successive seasons under Wenger.
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