Ian Blackwell collected the remarkable figures of five for seven against his former Somerset colleagues as Durham closed in on their second successive LV County Championship title.

Durham have a game in hand on their visitors, who arrived at Riverside 30 points adrift and needing a win to retain any hope of staying in the race.

But once Blackwell's left-arm spin had completed their collapse from 89 without loss to 174 all out, their chances of victory looked slim.

They were no brighter at the close with Shivnarine Chanderpaul unbeaten on 49 out of Durham's 110 for three.

Somerset's hopes rose briefly when Charl Willoughby removed Michael Di Venuto and Will Smith with successive balls with the total on 24, but Chanderpaul and Kyle Coetzer put on 80 before the Scot was bowled by Ben Phillips for 30, one over before the close.

Durham were bolstered by the return of Graham Onions and Steve Harmison from England duty, but Liam Plunkett was the pick of their seamers.

After taking three for 169 in the last three championship matches his batting average of 46.5 probably helped him survive at the expense of Mark Davies, but he would have had a five-wicket haul but for two dropped slip catches.

With a break for lunch after six overs, Plunkett bowled unchanged for 21 overs and finished with three for 65. There were two wides in his second over, but once he found his line he shaped the ball away from the right-handers at good pace.

Onions removed both Marcus Trescothick and Justin Langer after seeing his opening ball of the match edged by Trescothick past Callum Thorp's right shoulder at third slip.

Arul Suppiah played very nicely through mid-wicket and dominated the stand as runs flowed at four an over, reaching 50 off 70 balls with nine fours.

But both he and Trescothick fell with the total on 89, the former England left-hander departing first for 31 when he played a loose shot wide of off stump and was well caught by Smith at gully. Then Suppiah drove at Plunkett and edged to Phil Mustard.

Langer should have gone for two when Chanderpaul dropped a regulation catch at first slip off Plunkett, but he added only ten before an excellent ball from Onions swung in to bowl him.

Harmison briefly left the field after bowling one over in his second spell. Blackwell came on and struck in his second over.

James Hildreth had made 27 when he pushed firmly forward with an open face and steered a catch straight to Thorp at second slip.

Plunkett's away swingers accounted for Peter Trego and Craig Kieswetter, both well caught by Di Venuto low to his left at second slip.

Then successive balls from Blackwell had Zander de Bruyn and Ben Phillips lbw before Alfonso Thomas edged to Di Venuto and left-hander Willoughby was beaten by the turn and bowled.