Mitch Claydon, Yorkshire's burly Australian-born rookie paceman, virtually assured himself of a Championship debut later this week with two dynamic bursts of bowling in the match against Leeds-Bradford Universities at Headingley yesterday.

The 23-year-old fast bowler, whose father comes from the village of Markington, near Harrogate, claimed figures of 5-37 as the students were bowled out for 169 to leave Yorkshire with an overwhelming first innings lead of 377.

Yorkshire then opted for further batting practice rather than enforcing the follow-on and Michael Lumb, in first to compensate for his first innings failure, survived a chance to the wicketkeeper on 20 to complete his century off 127 balls with 17 fours and two sixes and Matthew Wood was again in the runs with 98 from 85 balls with 17 fours and a six.

Lumb was unbeaten on 109 when the declaration came at 266-5, leaving their opponents to make an improbable 644 to win today.

Deon Kruis's calf injury and Jason Gillespie's absence on Test duty for Australia mean that fast bowling places are up for grabs in Wednesday's Championship curtain-raiser at Trent Bridge and Claydon staked his claim in style.

His first four overs with the new ball in the morning cost him 18 runs, mainly from edged boundaries, but he hit back by producing a real snorter which almost took off Adam Patel's head. Instead, it grazed the shoulder of the bat for wicketkeeper Gerard Brophy to hold the catch.

In his next over, Claydon shattered Gharib Nawaz's stumps with an express yorker before he was given a rest but in the afternoon he returned to wreak more damage, dismissing Robert Sutton and Farhan Khan with consecutive balls and getting Amar Rashid out.

Yorkshire in their first innings racked up 546-7 declared in 100.2 overs with Joe Sayers, Anthony McGrath and skipper, Craig White, all helping themselves to what will be their easiest centuries of the season.

McGrath, particularly, was in ruthless form, smashing 151 before retiring.

Updated: 10:23 Monday, April 17, 2006