Darren Lehmann should know later today if he will be fit to play for Yorkshire in tomorrow's Championship encounter with Derbyshire at Derby after a scan on his stiff back.

The Australian has been restricted in his movements over the past few days and was rested from Sunday's game against Somerset.

Director of cricket, David Byas, said: "We don't think that Darren has got a serious problem but because it has gone on for some time now it was felt it would be wise for him to have a scan."

The stiffness in Lehmann's back may be the result of the extensive travel he has done over the past few months. Since arriving at Headingley just before the start of the season, he has travelled to Zimbabwe as well as returning home for Australia's two Test matches against Sri Lanka.

Lehmann is on the team sheet for tomorrow's match but if he has to pull out his place will be taken by Vic Craven.

Definitely missing will be Chris Silverwood, who has had an injection on a sore heel which started to bother him last Thursday, and into the squad of 12 come pacemen John Blain and Nick Thornicroft.

Although Byas is still upset at the way Yorkshire capsized in their Championship match with Somerset last week, he has been heartened by the way they played against the same team on Sunday in the totesport League.

"It was good to win on the back of some excellent batting by our home grown players for a change instead having to rely on someone from overseas," said Byas.

"Matthew Wood is in really good form at the moment and I was delighted with the way Michael Lumb and Andrew Gale scored their runs."

Yorkshire (from): Wood, Gale, McGrath, Lehmann (or Craven), Lumb, Harvey, Dawood, Dawson, Blain, Thornicroft, Gray, Kirby.

* Vikram Solanki hit his third one-day century of the season to help Worcestershire maintain their totesport League promotion challenge with a 34-run win over Division Two rivals Somerset at Taunton.

The opener scored 122 out of his side's modest 225, hitting 14 fours and two sixes in his 114-ball innings.

The only real support came from Steve Rhodes, who contributed a crucial 33 late on as Nixon McLean claimed four for 35 for the visitors.

Somerset looked to be in control when Ricky Ponting (46) and James Hildreth (31) took them to 90 for two.

But good bowling from Kabir Ali (3-28), Andrew Hall (3-24) and Gareth Batty (2-37) saw the Royals fight back and dismiss the visitors for 191.

John Francis did his best to steady the Sabres with 38, but struggled to score at the required rate as his side suffered their fourth successive defeat in the competition.

Solanki had held the Worcestershire innings together in confident style, adapting his innings to the circumstances perfectly.

He hit 11 boundaries in reaching his half-century off 45 balls, but then reined himself in, striking only two more in getting to three figures off 105 deliveries.

There was scant support after an opening stand of 48 with Stephen Moore as McLean ripped through the top order, sending back Graeme Hick, Ben Smith, David Leatherdale and Andy Bichel in two spells.