The Senegal international has had a chequered past involving unsavoury spitting incidents with fans and opponents.

Click for latest transfer gossip>>

Though such flashpoints of the past appear to have been quelled, the attacker – capable of playing in midfield or up front - still collected 16 yellow cards last season.

As a man who was judged by many who did not know him when he was a player, Sunderland boss Roy Keane will not fall into the same trap with Diouf – who signed a four-year deal on Wearside last night.

Keane said: "You have to be careful with what you hear about players from other people.

"One thing I don't do as a manager is ring people and try and get opinions on players – I want to gauge them for myself.

"You never really know with any player you buy, but if I want to be a top manager then I can't shy away from different types of characters."

Diouf, 27, became Keane's fifth summer signing but the deal didn't go through in time for him to feature in last night's 4-0 win over Cobh Ramblers in Cork.

The Sunderland boss still hopes for more new faces in the near future.

He said: "We need more players because last year we were found out when we picked up a lot of injuries.

"I'm a big believer in competition for places at football clubs and I am hoping there will be one or two more players coming in over the next two or three days.

"El Hadji is a great signing for us and we're thrilled to get him in.

"He has bags of Premier League and international experience, which is exactly what we've been targeting this summer."

SEE Tuesday's Mail for full story