McClaren, who has spent three years as Sir Alex Ferguson's number two at Manchester United, will take over as boss at the Riverside following the departure of Bryan Robson last week.

Robson ended his seven-year reign at the helm after another disappointing season on Teesside.

The 40-year-old is expected to sign a five-year, �1m-a-year contract.

He earlier told newspapers that moving to the Riverside was both "hardest and easiest decision I have ever made".

"People say that nobody in their right mind would leave Manchester United and 99 times out of a 100 that would be true," he said.

"I realised I was well down in the pecking order. I had reached a stage where I needed to take a change in direction and the chance to manage a terrific club like Middlesbrough provided it," he said.

"As soon as I spoke to Middlesbrough chairman Steve Gibson I knew it was the club for me.

McClaren, 40, returned from a family holiday in Florida at the weekend before holding further talks with Gibson.