Clarke firms Australia's position

Australia vice-captain Michael Clarke extended his excellent form with the bat to enhance the tourists' position in the fourth npower Ashes Test this morning.

Clarke, the leading run scorer in the series, passed 50 for the fourth time in the campaign and has now scored more than 400 runs off the England attack.

He was unbeaten on 60 in Australia's 237 for four, a lead of 133, after a free-scoring opening half-hour to the second morning at Headingley.

Fifth-wicket partner Marcus North set the tone for the day when he punched the third ball, from James Anderson, through the covers for four to bring up a half-century stand, of which his own contribution was 11.

England required a good start with the ball after their horror show yesterday but Steve Harmison served up a long hop with his first ball from the rugby stand end, which was clattered through mid-on by Clarke.

A repeat of the stroke in the next over put Clarke on the verge of 50 and he got to the mark, from 78 balls, in the sixth over of the morning.

Meanwhile, Australia all-rounder Andrew McDonald has temporarily quit the tour to attend the birth of his first child.

McDonald, 28, is expected to return here on August 13, in preparation for the final npower Ashes Test.