The England scrum-half, who had been due to win his 12th cap, has a ligament strain.

Coach Clive Woodward admitted the injury was not severe, but said he could not risk him.

"The strain means that Matt will be 95% fit, but I am only going to pick players who are 100%," he said.

Dawson was appointed captain for the demanding tour to Australia, New Zealand and South Africa when Lawrence Dallaglio withdrew because of a persistent shoulder problem.

His injury is another setback to a tour which has already seen the withdrawal of several key players because of a club vs country clash.

Jeremy Guscott, Martin Johnson and Neil Back are all missing, but Dawson's absence is particularly galling for Woodward after England put in some sharp and intense training under his guidance.

The Saracens skipper and number eight Tony Diprose takes over the captaincy from Dawson while Gloucester's Scott Benton has been drafted for his first cap.

Bradford-born Benton, 23, acted as Dawson's understudy against Scotland and Ireland in this year's Five Nations Championship.

He scored a try for England A against New Zealand at Leicester in December, before that he captained England Colts and played England Under-21 rugby.

Benton was snapped up by Gloucester from Leeds club Morley in 1995 and has improved steadily with expert tuition from Gloucester coach and former England scrum-half Richard Hill.

Benton will be the fifth new cap taking the field on Saturday, joined by Richmond wing Spencer Brown, Saracens pair Steve Ravenscroft and Ben Sturnham and Sale flanker Pat Sanderson.