Hampshire must spend a second season in Division Two after losing by 122 runs to Essex at the Ageas Bowl despite a valiant unbeaten 139 from captain Jimmy Adams.
Resuming on a seemingly hopeless 73-3 with another 352 required to take their promotion battle into the final fixture, Hampshire were all out by mid-afternoon for 302.
Essex would have completed their victory sooner had it not been for the dogged Adams, who featured in stands of 160 for the fourth wicket with Liam Dawson and 62 for the last with David Griffiths.
Adams and Dawson took the score to 183 before the latter offered Ryan ten Doeschate a return catch, and with him went Hampshire's last chance of averting their fourth defeat of the season.
Graham Napier removed David Balcombe after an eighth-wicket partnership of 27 and then James Tomlinson, who was bowled without scoring in the same over.
Griffiths and Adams stubbornly stayed put for a further 20 overs until Reece Topley ended the unexpected resistance by bowling Griffiths at the start of the 85th over, consigning Hampshire to their fate.
Hampshire's promotion hopes suffered a major setback on day three of their Division Two match with Essex, where they were set the highest fourth-innings score to win an LV= County Championship match.
Set a daunting 427 for victory at the Ageas Bowl, Hampshire were struggling at 73-3 at stumps on the penultimate day. They require a further 354 runs to win, with seven wickets intact.
Essex, well-placed on 217-2 at start of play, were eventually dismissed for 475, with Owais Shah taking his unbeaten 124 overnight on to a chanceless 161.
Ryan ten Doeschate added impetus to the Essex innings down the order, sharing a breezy 89-run stand with captain James Foster, who himself posted 61 to take the lead beyond 400.
Hampshire's already slim prospects of chasing down such a sizeable total were dealt a triple blow in the final 20 overs of play - all at the hands of Maurice Chambers.
Michael Carberry (six) was caught by the Jamaica-born paceman before Bilal Shafayat (three) and former Australia Test left-hander Simon Katich (nought) perished to his bowling before stumps.
Hampshire's promotion hopes were stifled by Owais Shah as Essex took command on day two of their Division Two clash at the Ageas Bowl.
Shah shared a huge stand with Jaik Mickleburgh as Essex reached 217-2 at stumps, a lead of 168 that could prove very troublesome for the promotion chasers.
Hampshire could do with winning their last home game of the season - they face leaders Derbyshire in Derby next week - but their hopes of a big first-innings lead were ended by Reece Topley.
The England U19 seamer accounted for Bilal Shafayat and James Vince in his first two overs on his way to figures of 3-59.
Sean Ervine scored 43 at the end of the Hampshire innings but 229 would have been a disappointing total after most of their top seven got a start.
Essex lost Tom Westley for 15 but his dismissal sparked a stand of 193 between Mickleburgh and Shah, who hit 20 fours and a six in his unbeaten 124 that frustrated home fans.
Mickleburgh departed for 73 to the occasional spin of Simon Katich four overs before the close but Essex are in position to set a daunting chase on Thursday.
David Balcombe took 4-57 as Hampshire gave their promotion hopes a boost by bossing the first day of their LV= County Championship clash with Essex at the Ageas Bowl.
Balcombe took his haul of wickets for the season to 52 as the visitors were bowled out for 180 after losing the toss, with Hampshire responding by reaching 165-4 at stumps.
It proved to be a good toss for Hampshire captain Jimmy Adams to win, with the top six Essex batsmen out to slip catches and three more snared by wicketkeeper Michael Bates. Sean Ervine bowled Tom Craddock for nine to account for the other wicket.
Mark Pettini was the only batsman who provided any real resistance to Hampshire's march to maximum bowling points as he top-scored with 58. Graham Napier (26) helped him out to some extent in a seventh-wicket stand of 54.
Despite Adams falling for just eight in the seventh over, Hampshire found batting far easier with Michael Carberry making a rapid 42 before being snared by Maurice Chambers.
Bilal Shafayat also made 42, although he remained unbeaten at the close of play, while James Vince also looks well set on 22 not out.