Rich Pyrah will be out for up to a month after dislocating his right knee while batting against Kent at Canterbury on Sunday.

Pyrah got his studs caught in the turf during the Clydesdale Bank 40 win, although things are not quite as bad as first feared for the in-form all-rounder because Monday's scan showed no ligament damage.

The 28 year-old has taken 15 wickets and scored 117 runs from four Championship matches, added to four wickets and 72 runs from his three 40-over matches.

"We've been told that he will be out for between two to four weeks, but we won't rush it because of the workload that bowlers have to get through," said captain Andrew Gale.

"We'll probably have to put him through some second team cricket first, but he should be back in time for Twenty20 on June 3."

Yorkshire play four LV County Championship matches before they face Warwickshire in their 20-over opener at Headingley, including today's home fixture against struggling Hampshire.

The loss of Pyrah is at least offset by Tim Bresnan's availability for the next two matches - the second of those being the Roses match against Division One leaders Lancashire at Liverpool next Wednesday.

Bresnan has had injury problems of his own, struggling with a calf injury through the second half of the recent winter. He was forced to return home early from Australia before battling through the latter stages of the World Cup.

Now the 26 year-old, who returned to county action in that 40-over match at Canterbury, is fit again and raring to go as he aims to retain his place in England's Test side for the forthcoming series against Sri Lanka.

He is vying for the third seamer's spot - Jimmy Anderson's and Stuart Broad's places look secure - with the likes of Ashes colleagues Chris Tremlett, Steven Finn and county colleague Ajmal Shahzad.

He said: "There are so many of us vying for the spots and everybody is fit. There are a lot of good fast bowlers to pick from.

"That's why these two Championship games before the Test are really important for me. I need to get some miles into my legs and rhythm back into my bowling."

Bresnan today plays his first first-class match since January when he played against the Australians at the SCG in the fifth Test, and his first LV County Championship match for Yorkshire since last August.

Like county colleague Shahzad and England team-mate Broad, Bresnan has also spent the bulk of his time recovering from his injury since returning home from India early last month.

He said: "I'm excited about this week. It feels like I've been in rehab forever, doing drills and stuff. I just want to get out and play now.

"It obviously takes a while to get back into the swing of things. It's different in the nets and hard to recreate the intensity of a match situation.

"It might take a day or two of Championship cricket, but I should be fine."