West Ham, who have been steadily plugging their once leaky defence in recent seasons, continue the process today with the debut at Coventry of the Chilean international Javier Margas, described by the Hammers' manager Harry Redknapp as "a genuine hard nut".

Margas, who plays in place of Ian Pearce who has a septic foot, joined West Ham in the summer from Universidad Catolica in a £2 million deal.

"You have only got to look at him to see that you wouldn't like to get on the wrong side of him," said Redknapp. "He is a powerful lad who trains like a demon, likes to tackle and is a great header of the ball. He plays the game hard but fairly.

"He has impressed me as a person and I don't think he can fail to do well because he is an educated boy and his attitude is so good. He is a quiet lad who just gets on with his job, a bit like a silent assassin, and the opposition will know they've been in game with him."

Margas has 55 caps for Chile, and Redknapp secured first option on him last April after the friendly against England at Wembley. The West Ham manager then watched the 29-year-old in the World Cup and completed the deal.

West Ham will have Ian Wright and John Hartson together in attack for the first time, but Trevor Sinclair is doubtful with a groin strain.

Middlesbrough's Mikkel Beck gets his first start of the season against Derby at the Riverside Stadium. The Denmark striker has had to settle for a place on the substitutes' bench for Middlesbrough's opening two Premiership games, but he scored when he appeared as a second-half substitute in Middlesbrough's 3-1 defeat at Villa Park on Sunday.