Gilberto: Arsenal could end up like Moyes' United if Wenger leaves

Ferguson spent an astonishing 26 years at Manchester United where he won 13 Premier League titles two Champions League titles and five FA Cups, among other trophies.

However, since Ferguson left United in 2013, the Red Devils have not reached the same heights as they did under the Scot, winning just one FA Cup and qualifying for the Champions League on just one occasion.

Gilberto believes that something similar may happen at Arsenal if the country's longest-serving manager leaves the club. Some believe that Wenger should leave having not won the Premier League title since 2004.

"Arsene at this time is facing a lot of criticism for the way the team play and they haven't got the trophies," Silva said.

"But if people see the entire job he has done for the club, it has been amazing. I hope people do realise that, because when he leaves the club at some point it won't be so easy to replace him.

"You can see, for example, at Manchester United where it's not been so easy to replace Sir Alex Ferguson. It's important for Arsene and for the club to start to prepare somebody for when he leaves".