DURHAM have run into early problems in their search for a replacement overseas bowler for the last month of the season.

Victoria seamer Mick Lewis has rejoined them for the match against Somerset starting at Taunton today but is available only until mid-August.

Although Ashley Noffke is to have another scan on his back problem in Newcastle, Durham are resigned to his season being over and have already started looking for another replacement.

"Mike Hussey suggested a couple of Australians, but it seems they are already going to other counties, so it's looking a bit tricky," said coach Martyn Moxon. "It might have been an idea to sign a world-class spinner but there aren't any available because of Test and one-day series."

Moxon was more hopeful last night that Mark Davies will be fit to play at Taunton after suffering from back stiffness during the match at Derby. His condition improved following treatment yesterday, but if he doesn't feel right this morning Australian swing bowler, Callum Thorp, will make his championship debut.

Despite the draw at Derby, Durham stretched their lead over Lancashire at the top by one point to 12 as neither the Red Rose men nor visitors Essex were able to take full bowling points from the high-scoring draw at Old Trafford.

More importantly, Worcestershire's defeat by Northants gave Durham a 23-point cushion over the fourth-placed side.

Gareth Breese will be looking forward to returning to the scene of his finest hour, which saw him score 165 not out in Durham's one-wicket win at Taunton last season.

His second highest score for Durham was the 79 not out he made in the four-wicket win against Somerset at Stockton in May.

Durham are also hoping for an improvement from Phil Mustard, who was showing signs of fatigue at Derby, where he made nought and let through four lots of four byes. They will have to persevere with him as they don't have the option of bringing in Andrew Pratt, who is believed to have asked for his release.

Somerset, third from the bottom with only two wins out of nine, will be led for the final time by South African captain Graeme Smith.

Durham (from): M E K Hussey (capt), G M Scott, P D Collingwood, G J Muchall, D M Benkenstein, G R Breese, P Mustard, L E Plunkett, M Davies, G Onions, M L Lewis, C Thorp.

* Chris Silverwood returns to Yorkshire's side for the Championship match against bottom club Derbyshire at Headingley today in what could be one last chance for the former England fast bowler to resurrect his career, writes DAVID WARNER.

Silverwood, 30, was dropped after the opening match of the season at Chelmsford when he conceded 72 runs to the Essex batsmen without picking up a wicket.

He was told to rediscover his pace in the second team and he missed a couple of Championship matches before returning for the games against Durham at Riverside and Essex at Headingley.

Silverwood bowled a tight opening spell in the Essex game, but still looked well below his best and, with three outings having brought him just three wickets at 79.33 runs apiece, he dropped into the reserves again.

Yorkshire's bowling coach Steve Oldham insists Silverwood is up to the mark but he needs to start taking wickets to convince director of cricket David Byas that he has still got it in him to bowl quickly and effectively.

Byas said: "Chris has now got the chance to show that he is as good a bowler as he was before the ankle injury on which he had an operation at the end of last season.

"I will be absolutely delighted if he can show us that he is because Chris is a very experienced bowler and we need him in the side taking wickets."

With the Headingley pitch unlikely to assist the slow bowlers, Silverwood comes in for leg-spinner, Mark Lawson, in what is the only change from the side which so spectacularly completed the double over Leicestershire at Scarborough on Saturday.

Left-arm paceman, David Lucas, was 12th man at North Marine Road and he may have won the vote over Silverwood for today's game had he not bowled so disappointingly against Warwickshire Bears on Sunday when he failed to pick up a wicket and lacked control.

Winning their last two Championship matches has seen Yorkshire lift themselves into the third promotion spot and they still enjoy a game in hand over their rivals.

They are the only unbeaten side in either division and Derbyshire are the only Second Division team not yet to have won a match, although they are getting stronger and against Durham they made 539 for seven declared in their second innings after being forced to follow on, Australian Michael Di Venuto hitting a double century.

Rain caused that game to end in a draw but in setting a target of 330 with plenty of time remaining Derbyshire showed they are prepared to gamble to win.

Yorkshire: Sayers, Wood, McGrath, Jaques, Harvey, White, Dawood, Bresnan, Dawson, Silverwood, Kruis.

Read more about Durham here.