Roy Keane has landed his fifth summer signing after Norwich City were forced to accept a £1.5million bid for their Nigerian midfielder Dickson Etuhu.

The 25-year-old, linked recently with Everton and Middlesbrough, rejected an improved contract offer from the Championship side over the weekend once Sunderland's interest became known.

He completed a medical at the Stadium of Light this morning and signed a four-year contract.

"I'm very pleaded that Dickson has signed," said Keane.  "He will add competition to our squad and give us a real physical presence.  He's a big, strong player who can also get a goal."

Keane's bid activated a buy-out clause in the player's contract and Norwich chief executive Neil Doncaster had little option but to accept Sunderland's offer.

"We are very disappointed to lose Dickson obviously, but the simple facts are Dickson turned down the offer of a new, more lucrative contract from Norwich in favour of Sunderland's offer," he said.

"We are therefore forced to accept their offer under the terms of his contract."

A combative midfielder with an eye for goal, Etuhu took time to win over the Norwich faithful following his £450,000 arrival 18 months ago after an initial loan spell at Carrow Road.  He joined the club following spells with Manchester City and Preston North End.

Etuhu becomes Keane's fifth acquisition following Greg Halford, Russell Anderson, Michael Chopra and Kieran Richardson's respective arrivals.

The manager has also refused to rule out further signings.  "We're definitely heading in the right direction as far as getting the players we want to the football club," he said today.

"The signing of Dickson creates competition and a club like Sunderland needs that. "We all talk about the big four having competition for places, I feel every club should have it and that's what I'm trying to do here.

Richardson, who joined from Manchester United yesterday, is relishing the prospect of again working with Keane - his former Old Trafford team-mate.

"It's an exciting move for me," the England international said.  "I know all about Roy Keane and I'm looking forward to playing for his team.

"He told me all about his big plans for the club and I wanted to be a part of that.  Sunderland is a big club and it's a great move for me.  I can't wait to get going."

But neither Richardson or Chopra will play in tomorrow's friendly against Darlington.

Keane would prefer both train for the remainder of the week before possibly making their debuts against Scunthorpe on Saturday.  Anderson and Halford should feature tomorrow.

Anthony Stokes and Daryl Murphy are also unlikely to play against Darlington following their exertions on the Republic of Ireland's recent tour to the United States.

Finally, Keane has also been linked with a move for his former Celtic team-mate Bobo Balde of whom both Newcastle and Blackburn made enquiries last summer.

But the big defender still has two years remaining on his Celtic contract.  While it is thought he is keen to stay in Glasgow he could yet be persuaded to turn his hand to the Premiership.