Northamptonshire 175 (Procter 40, Abbott 4-52, Barker 3-41) and 153 for 3 (Gay 74) trail Hampshire 400 for 9 dec (Donald 94, Organ 71, Abbott 57) by 72 runs
Hampshire snared 12 wickets in the day to roll Northamptonshire for a first-innings 175 and claimed full bonus points to put themselves on course to go top of the LV= Insurance County Championship Division One.
Kyle Abbott took his season tally to 53 wickets to remain the leading wicket-taker in Division One with 4 for 52, while Keith Barker joined him in second with 3 for 41 and 1 for 34.
Northamptonshire were forced to follow on after suffering a 225-run first-innings deficit, but Emilio Gay's excellent season continued with a classy 74 as the visitors ended the day 153 for 3 - still 72 runs behind.
Hampshire will go at least level with leaders Surrey, who do not play in this round, with a victory moving them eight points clear.
After a fair batting day, conditions very much favoured bowling, with Barker, Mohammad Abbas and Abbott relentless in their probing.
With such heavy rain coming overnight and in the morning, it was a testament to Simon Lee and his ground staff - along with the new outfield laid last winter - that play started only 45 minutes later than scheduled.
When it did Hampshire needed just five overs to make their first breakthrough. Gay had been almost perfect in his defence the previous evening but clipped to square leg with only three runs added in the morning.
From then on it was rather a procession, with the remaining eight wickets falling in 33 overs.
Josh Cobb pulled to the catcher at short mid-wicket, Rob Keogh edged behind to Aneurin Donald for a 10-ball duck, and Ricardo Vasconcelos - having unfurled a lovely cover drive first ball - pushed to second slip.
After lunch, James Sales was yorked to the first ball on resumption by Barker.
Luke Procter had ground out 40 at the other end with watchfulness and skill against the moving ball, but his downfall was a James Fuller over always destined to take a wicket.
Fuller, in his first over of the match, bowled two short balls to destabilise Procter, then beat his outside edge before clipping the edge of the bat with the final ball of the over, a snorter.
Tom Taylor had attempted to dig in but edged behind, Lizaad Williams sliced to point and Ben Sanderson was bowled to wrap things up, and Northamptonshire were sent straight back in with a 225-run deficit.
A fresh innings saw a return to Gay and Will Young bedding in. The duo put on 68 in the first innings and looked unmovable when amassing 98 in the second.
Gay was particularly impressive in his fifth half-century of the campaign, refusing to get bogged down with crafty shot-making while still valuing his wicket.
Young was less fluent, with three-quarters of his four boundaries coming when the bowling erred onto his pads. He largely avoided playing at anything he didn't need to until Ian Holland forced him to nibble at one on a fourth-stump line to nick behind.
Procter was also victim to a jaffa as Barker found bounce just back of a length to also edge behind, before Gay was lbw to Fuller two overs later. Bad light once again ended the day early.
