Surrey are 151-7 (Nicholson 40*, Ormond 35*), a lead of 202

Sean Ervine believes he is returning to his best bowling form since suffering a career-threatening knee injury three years ago.

The Hampshire all-rounder produced a devastating spell of 3-1 in 17 balls as Surrey slumped to 75-7 in their second innings at the Rose Bowl yesterday.

Ervine finished with 3-26 from his ten overs after taking the prize wickets of Mark Butcher, Ali Brown and Usman Afzaal before Surrey recovered to close on 151-7.

It was the most threatening Ervine has been with the ball since his debut season in 2005, which ended with knee reconstruction when he suffered cruciate ligament damage in the final game.

Surrey ended the penultimate day with a lead of 202 after an unbroken 76-run stand between Matt Nicholson (40*) and Jimmy Ormond (35*).

But Ervine's performance was a major boost for Hampshire on a day that began with the news that Chris Tremlett is struggling with a back spasm and was unable to bat or bowl, having taken 5-67 in Surrey's first innings.

Ervine said: "I've been trying to get more consistency, control and balance at the crease for a while now.

"My pace comes from being able to brace my front leg and it's slowly coming back to how I was bowling in 2005.

"I've felt really good in some spells playing for Western Australia but this is probably the best I've felt while I've been here in the UK.

"When you have a cruciate injury in your leg it takes a lot of time and effort to be able to feel confident in your knee but the knee feels really strong now."

Ervine took 42 Championship wickets at 32.38 for Hampshire in 2005 and today's three-wicket burst took him to 42 wickets at 44.83 in the 24 first-class games he has played since.

After Hampshire had been dismissed for 227-9, a first-innings deficit of 51, left-hander Scott Newman edged the fifth ball of Surrey's second innings to third-slip Chris Benham.

Dimitri Mascarenhas then trapped Jon Batty and Mark Ramprakash lbw in successive overs from the Northern End.

Ramprakash will have to wait at least another week for his 100th first-class hundred and was a little unfortunate as he had taken a good stride forward.

But umpire Barry Dudlestone did not think so and Ervine responded with his inspired six-over spell from the Pavilion End.

Captain Butcher was pinned lbw by an inswinging yorker, Brown got a nick and left-hander Afzaal was brilliantly caught by a diving Tom Burrows in front of first slip.

James Tomlinson and Benham combined for the second time when Chris Jordan was caught at third slip.

But Nicholson and Ormond frustrated Hampshire before bad light brought the day to a premature close.

Hampshire bowling: Tomlinson 14-3-55-2,Mascarenhas 19-7-49-2, Ervine 10-2-26-3, Lamb 7-0-13-0