Vice-captain Joe Leach claimed his third five wicket haul of the season in Specsavers County Championship cricket as Worcestershire obtained a first innings lead of 129 in the clash with Northamptonshire at Wantage Road.

Then a century stand between openers Daryl Mitchell and Brett D'Oliveira – their third of the campaign – helped Worcestershire extend their overall advantage to 310 by the close on a dry wicket showing signs of starting to turn.

Leach finished with 5-70 from 18.1 overs as Northants were bowled out for 148 in 45.1 overs three quarters of an hour after lunch on day two.

It followed on from his 5-115 against Essex at New Road and 5-99 versus Leicestershire at the Fischer County Ground.

Leach has now taken 36 Championship wickets this summer – a figure only bettered in Division Two by Leicestershire's Clint McKay.

He received excellent support from fellow new ball bowler Matt Henry (3-52 from 17 overs) and spinner D'Oliveira (2-3 in three overs).

D'Oliveira then completed an excellent all-round day by top-scoring with 81 from 163 balls with five fours as the County closed on 181-4.

Northamptonshire resumed on 64-3 and in a rain interrupted morning session lost three wickets for 50 runs in 17 overs – two of them to New Zealand paceman Henry.

Richard Levi (27) attempted to pull a bouncer from Henry and top edged a catch to keeper Ben Cox running back.

In the next over Leach claimed his fourth wicket when Steven Crook was caught by skipper Daryl Mitchell at second slip.

Adam Rossington reached an accomplished 50 off 61 balls but in the penultimate over before lunch he was undone on 55 by a fine away swinger from Henry as Cox took an excellent catch diving to his left.

The wickets continued to tumble after the interval as Seekkuge Prasanna (4) was safely pouched at second slip by Mitchell off Henry.

D'Oliveira was brought into the attack for the first time and he enjoyed an instant success with the last ball of his first over as Azharullah (7) was trapped lbw.

It became two wickets in two balls for D'Oliveira as Ben Sanderson departed in the same manner.

Monty Panesar survived the hat-trick ball but Leach returned to wrap up the innings and claim his fifth wicket as David Murphy (23) perished to D'Oliveira at point.

Worcestershire had run into early trouble in their first innings but Mitchell and D'Oliveira negated the threat of Azharulah and scored around four runs an over.

The 100 partnership came up in the 28th over and followed on from the 113 against Sussex and 179 versus Essex posted by the pair this summer – both at New Road.

Prasanna broke the stand with the last ball of the same over as Mitchell (47) was trapped lbw with 104 on the board and the overall lead then 233.

D'Oliveira and Tom Fell further strengthened Worcestershire's position with a stand of 73 in 24 overs before three wickets fell for three runs.

D’Oliveira was composed and clever, scampered keenly between the wickets and tucked Prasanna finely past short square leg for a a fifty in 92 balls with three boundaries.

He lifted Rob Keogh down the ground for four over long-on but shuffling down the pitch again, Keogh fired a ball down the leg side and Murphy completed a smart stumping with D’Oliveira 19 short of a third century of the season.

Keogh struck again next ball when bowling Joe Clarke (0).

Tom Kholer-Cadmore survived the hat-trick but was trapped lbw by Prasanna for a 13-ball duck to leave Fell unbeaten on 36 from 95 balls with three fours at the close.