THERE was some relief at the end of a hugely frustrating day for Durham after they were made to toil under a cloudless sky while Jason Roy rode his luck to score 120.

Graham Onions finally removed him in finishing with four wickets as Surrey slipped from 264 for three to 299 for seven, 102 behind.

Durham were twice convinced they had Roy caught behind, but there were no edges from the England one-day batsman - he either middled it or missed it.

Until he reached 70 Roy looked as though he could be out at any time, but he had a secure ally in Zafar Ansari, who was happy to be the sleeping partner in a stand of 164.

When the pitch looked flat in the afternoon it suggested Durham had batted poorly in support of Keaton Jennings, who was left stranded on 201, becoming the seventh player to carry his bat through a Durham innings.

He now has 1,511 runs this season with potentially three innings to beat Michael Di Venuto's club record of 1,654, set in 2009.

Although the welcome fifth batting point was achieved when Onions scored the day's first seven runs, he then drove a catch to cover and a total of 401 looked a little light for absolute safety.

The late wickets reduced the fear that Surrey could build a big enough lead to put Durham under pressure, and increased the chances of a win which would clinch a 12th season in division one.

A draw will take Durham to the Ageas Bowl, which is bound to be a dustbowl prepared for the spinners, in the relative comfort of knowing they are ahead of Lancashire and Warwickshire, who play each other.

Lancashire looked like subsiding tamely against Middlesex yesterday, and despite a rally and help from bad light it still looks as though they will do well to emerge with more than a couple of points.

The only Surrey batsman to fall before lunch was Rory Burns, who was given an uncomfortable time by Mark Wood, achieving steep bounce with his shorter deliveries. But it was a full-length in-swinger which took the left-hander's inside edge on the way to wicketkeeper Stuart Poynter.

Faced with an attack of Wood, Onions, Ben Stokes and the pacy Brydon Carse, Dominic Sibley played well enough to suggest he won't be the one making way for Mark Stoneman, or Borthwick.

Carse, back after a three-month injury absence, posed the greatest threat. He beat Kumar Sangakkara twice in his first two overs then had a big appeal for caught behind turned down with Sibley on 25.

Onions took two wickets in four balls shortly after lunch. He beat Sibley's forward push on 31 to nick the off stump then nipped one back to have Sangakkara lbw for 48.

On 18 Roy edged Carse just wide of gully when looking to play to leg, then he hit Paul Collingwood's first ball just out of short extra cover's reach, and on 42 Onions had him in all kinds of trouble.

A ball which Roy played into the ground lobbed up and dropped just over the stumps, then he was beaten twice in the same over.

The runs began to flow once he had reached 50 off 103 balls, the next 50 coming off only 41, even though he still missed a few.

Ansari concentrated on survival, his one stroke of luck coming on ten. Collingwood posted his second slip well wide of first and the edge bisected them at waist height.

Durham turned to Jennings to fill in a few overs before the new ball was taken and Ansari edged a drive to slip to depart for 48.

Then Wood struck with his second delivery with the new ball and Onions with his first.

Ben Foakes was lbw when he walked across, looking to turn Wood to leg, then Onions skidded one through to knock Roy off his feet and claim another lbw verdict.

Onions produced another beauty four overs later to beat Tom Curran's forward push to trim his off bail and will be keen to complete his first five-wicket haul of the season today.