It was the second time in two games that bad light had forced a Northants player to wait overnight on 99 following on from David Sales in the last match at Bristol.

The 26-year-old finished one run away from a century after a 110-run partnership with stand-in South African skipper Lance Klusener.

The Proteas all-rounder finished on 62 not out as he and O'Brien salvaged Northamptonshire from 41 for two to 213 for four after they skittled the visitors out for 287.

Former County Ground employee Adam Shantry was the pick of the bowlers for Glamorgan taking three for 49 but received little help from his counterparts as Northamptonshire moved into a commanding position.

Johan van der Wath picked up where he left off at the end of day one removing former Northants pacemen Shantry for one to claim his fifth victim and bring Glamorgan's innings to a close.

Former Australian international Jason Gillespie took charge of the visitors' innings but could do little to stop O'Brien smashing Shantry to the fence six times in 16 deliveries.

However the 25-year-old persistence finally paid off when opener Stephen Peters edged him straight to Bermudan international David Hemp for one.

Shantry was clearly buoyed by his early scalp and quickly trapped incoming batsmen Rob White leg before wicket on eight as Northamptonshire slumped to 41 for two.

O'Brien and David Sales steadied the ship shortly after doubling the total to 85 but further misery ensued when the latter holed Alex Wharf to Mark Wallace for 23.

However it was not all doom and gloom for the home side with O'Brien quickly moving onto his half-century off 72 balls just before lunch with a four to fine leg.

Glamorgan flew out of the blocks after the interval and sent Riki Wessels packing for 10 – Shantry forcing the 22-year-old into a rash shot to allow Mike Powell an easy catch at second slip.

Northamptonshire had it all to do at 103 for four and Klusener's arrival was a timely one with the South African all-rounder capitalising on Hemp's dropped catch to fire them past 150.

Dean Cosker was shortly introduced to add some variation and could have made an impact if not for some poor fielding at silly point.

Hemp's day went from bad to worse when he again dropped Klusener and watched the stand-in skipper ease to 50 off 79 balls in the 61st over – the 11th time he has past his half-century in first-class cricket this summer.

Overcast skies greeted play after tea with Klusener and O'Brien taking the hosts past 200 before bad light stopped play after 73 overs.

Both sides returned after just a 10-minute break – but only four more balls were bowled before further bad light forced play to close, with O'Brien stranded on 99.