YORKSHIRE did not so much turn the screw as apply a suffocating tourniquet to Durham at Headingley yesterday.

Once the new ball had opened a crack in Durham's resistance it rapidly became a chasm as the champions accelerated towards a third successive title.

With a lead of 195, Yorkshire again declined to enforce the follow-on and Adam Lyth shared a stand of 185 with Alex Lees before going on to an unbeaten 114.

He went to his 135-ball century with a swept six off Ryan Pringle, which also took him to 1,000 championship runs two days after his opening partner.

Yorkshire's declaration on 225 for two, 420 ahead, left Durham with 16 overs to bat and they closed on 39 for three.

Once victory is achieved Yorkshire will be 15 points ahead if Middlesex fail to score the 190 they need with seven wickets standing at Trent Bridge.

Durham are in danger of being dragged deeper into a five-team scrap to avoid relegation.

If Hampshire convert their strong position into victory at the Oval and Durham lose, they will be level, one point ahead of Lancashire and two behind Warwickshire.

The interesting games next week are Yorkshire v Somerset, who are also in the title frame, Lancashire v Middlesex and Durham v Surrey.

In the final week Yorkshire are at Lord's, Warwickshire play their one remaining game at home to Lancashire, and Durham visit Hampshire.

Confirmation of the England one-day players' availability is still awaited, but even if Ben Stokes and Mark Wood are allowed one game each it would be a huge boost to Durham.

They battled hard to stay afloat on Tuesday, but as soon as the second new ball was taken yesterday they lost four wickets for 11 runs.

They had opted for batting depth with Michael Richardson at seven and Ryan Pringle at eight, but it was their misfortune to have to face high quality new ball bowling. Their frailty was cruelly exposed.

Durham lost their last six wickets for 38 runs to be all out for 265, despite the absence of Steve Patterson for family reasons.

With the floodlights on at the outset Yorkshire had to bowl the spinners. But after a brief break the dark clouds cleared and Jack Brooks had Graham Clark lbw for 25 with his second ball.

Pringle went the same way for one and Richardson edged the same bowler to second slip, where Lyth held a low catch, his third of the innings.

Jack Burnham had survived for more than three hours, facing 154 balls for 49, when Ryan Sidebottom produced a beauty to rattle his off stump.

Graham Onions repaid Sidebottom for bouncing him by lifting him for four to long-on followed by a straight six. He made 19 before he was last out when he tried another big hit off the left-armer and was bowled.

There was an air of inevitability about the afternoon proceedings as Durham toiled in vain. The best bowling came from Barry McCarthy, who came on after the spinners and conceded eight runs in five overs.

With 51 on the board after 12 overs Durham turned to spin at both ends and Lees had a slice of luck on 29 when a top-edged sweep off Pringle fell into space at square leg.

Lees pulled the off-spinner for six in his next over on his way to a 66-ball half-century. Lyth was two balls slower, but then forged ahead.

Lees reached 86 when he deposited a Pringle full toss over mid-wicket for six but added only two more runs before he drove at the off-spiner and was caught behind.

Pringle finished with two for 69 when Gary Ballance played on for 20, prompting the declaration.

In Durham's second innings Brooks was on a hat-trick when he had Mark Stoneman caught at mid-off when shaping to pull, then off the first ball of his next over drew Keaton Jennings forward to one which left him and took the edge.

Burnham was pinned lbw by a ball from Patterson which skidded on to him, leaving Onions to survive five overs as nightwatchman. It would be asking too much for him to repeat last week's vigil until after lunch today.

Durham won the Second X1 Championship final against Middlesex at Emirates Riverside by an innings and 117 runs.

The visitors were all out for 185 in the second innings, with Liam Trevaskis taking six for 31 with his left-arm spin.

The 17-year-old all-rounder from Penrith removed Ireland's Paul Sterling, who opened the innings and made 86, then took the last five.