Contrasting centuries by Niall O'Brien and Riki Wessels took Northamptonshire beyond 300 as honours finished just about even come the mid-point of their clash with struggling Surrey.

O'Brien's four-hour stay came to an end for 128 just before the close, leaving Rob White unbeaten on 63 as the visitors reached 331 for four - representing a first-innings deficit of only 45.

Despite excellent batting conditions, a rapid outfield and short boundaries, Northamptonshire made a dismal start to their reply by losing opener Stephen Peters and number three Alex Wakely to consecutive deliveries of the fifth over from Jade Dernbach.

Peters, cutting hard, was superbly caught low to right by a tumbling Matt Spriegel then, next ball up, Wakely pushed down the wrong line to lose his off stump and make it 28 for two.

Promotion-chasing Northamptonshire regrouped through an enthralling third-wicket stand of 159 in 31 overs between century-makers O'Brien and Wessels.

O'Brien had already reached 26 off only 16 balls when Wessels marched in to overhaul his partner and play the innings of the game in reaching his first century of the season from 94 balls with 14 fours and three sixes.

Rookie Surrey skipper Stewart Walters was left scratching his head as his injury-hit attack served up a selection of long-hops and half-volleys that allowed Northamptonshire to canter along at more than five an over.

With little threat from the bowlers or help from the docile pitch, it was almost inevitable that Surrey needed a run-out to break the stand.

Calling for risky second to long-leg following a sweep against Chris Schofield, Wessels ran himself out as Jonathan Batty whipped off the bails from an accurate throw from Rangana Herath.

O'Brien reached three figures from 150 balls and with 14 fours with a punch to the ropes through mid-wicket off Spriegel as he and White added 117 in 32 overs until the left-hander's 181-ball stay ended.

Having survived two big appeals to leg-spinner Schofield, O'Brien pushed at one that bounced and took the edge to fly to Walters at slip to make it 304 for four.

The Brown Caps' tail had earlier failed to wag at the start of the second day as they resumed on what appeared a promising overnight total of 305 for five.

Once Batty fell without adding to his battling score of 110, their innings slid away dismally as Surrey lost their last five wickets for 56 in space of only 16 overs.

Having stuck it out for over six hours Batty fell in the fourth over of the day when an attempted square drive against Johannes van der Wath picked out Peters at cover point.

Diminutive left-arm spinner Nicky Boje then got in on the act by removing Alex Tudor and Rangana Herath.

Having scored an attractive, counter-attacking 50 from 70 balls with two sixes and six fours, left-hander Schofield was guilty of tossing away his own wicket when he lost his middle stump to when slogging to leg against Andrew Hall.

The burly South African duly polished the innings off just before noon when he snared Jade Dernbach leg before.