Hampshire seized total control of their Specsavers County Championship match at Edgbaston – despite Warwickshire batsman Dominic Sibley scoring his sixth century in successive first-class matches.
Sibley carried his bat through the Bears' first innings for 109 and almost single-handedly staved off the follow on for hosts.
However, Hampshire will still enter the final day well-placed to harvest their second championship win of the season.
They secured a first-innings lead of 121 and then batted aggressively second time round to pile pressure on the injury-ravaged home side.
Rilee Rossouw (76), debutant Oliver Soames (62) and Sam Northeast (55 not out) enabled the visitors to declare on 302 for five, setting the beleaguered home side 424 to win.
In 20 overs batting before the close, Warwickshire reached 42 for two, losing openers Sibley and Will Rhodes, and they have a massive rearguard action ahead of them on the final day.
After Warwickshire resumed on the third morning on 184 for seven, they soon lost Henry Brookes, caught at slip off Joe Weatherley.
Sibley and Jeetan Patel saw their side past the follow on figure, before Gareth Berg dismissed Patel, caught behind, and bowled Olly Hannon-Dalby.
When Hampshire went in to bat again they showed immediate urgency and openers Soames and Weatherley (46) added 102 in 18 overs, before Soames pulled Craig Miles to mid-wicket.
Weatherley tickled Brookes leg-side to the wicketkeeper and Tom Alsop (25) was bowled, reverse-sweeping, by Patel.
But Roussouw ruthlessly climbed into the struggling attack either side of tea.
He struck four sixes and six fours to hurry the lead upwards with the objective of giving Hampshire's bowlers plenty of time to get at the home batting before stumps.
Roussouw skied Hannon-Dalby to deep mid-wicket but, after Liam Dawson fell lbw to Patel, Northeast and Aneurin Donald added a perky 38 from 33 balls to set up an early declaration.
With 20 overs to bat, Warwickshire lost Sibley to the 17th ball of the innings when he edged Kyle Abbot to wicketkeeper Alsop.
First-class debutant Rob Yates showed good composure in a high-pressure situation but Will Rhodes chipped Dawson to mid-wicket seven overs before the close.