Captain Ed Joyce hit his second hundred of the match to put Sussex on the brink of victory number two, over Warwickshire at Edgbaston, at the start of their LV= County Championship Division One campaign.
Joyce (125 not out) helped Sussex to a close-of-play 273 for two, in pursuit of 330, on day three - making a mockery of what appeared a tough chase, after Ian Bell's 189 not out for the hosts.
Bell's near seven-and-a-half-hour tour de force, containing 17 fours and three sixes, underpinned the Bears' 471 all out - Jeetan Patel (74) also making a significant contribution in an eighth-wicket stand of 118.
But Joyce then followed up his first-innings 117 to reach his 33rd first-class century with 11 fours from 172 balls, sharing an opening stand of 135 with Luke Wells (57) and then putting on an unbroken 85 with Rory Hamilton-Brown to leave only 57 more runs required.
Champions Durham also have a shot at victory, to open the defence of their title, against Northamptonshire at Wantage Road.
The hosts turned an overnight 200 for three into 378 all out, in reply to 452, thanks principally to Matt Spriegel's 97.
Seamers Usman Arshad (four for 78) and Jamie Harrison shared seven of the wickets, before Durham set about adding to their lead second time round.
At the close, Michael Richardson (53no) had helped them to 178 for five, despite four for 39 from Northants' veteran off-spinner James Middlebrook.
The option of a sporting declaration will therefore loom on the final morning.
At Lord's, Middlesex's prospective England opener Sam Robson extended his hundred to 163 off 310 balls out of 439 for nine declared against Nottinghamshire.
Wicketkeeper John Simpson (108no) also made his third first-class century, hitting 17 fours and a six from 202 balls in all.
Starting again 113 behind, Nottinghamshire nosed back in front on a vulnerable 184 for five - Steven Finn again in the wickets with three for 63.
A high-scoring draw looks likely at Taunton, where Somerset have replied to Yorkshire's 450 all out with 530 for nine.
James Hildreth (67), Craig Kieswetter (63), Johann Myburgh (91) and Lewis Gregory - with a career-best 69 - all added half-centuries to Chris Jones' a day earlier.
In Division Two, Alastair Cook - like his England team-mate Bell - turned his century into a very big one, finishing with 181 out of Essex's second-innings 425 all out against Derbyshire at Chelmsford.
James Foster (55no) also weighed in, while Tim Groenewald and Wes Durston shared six wickets - the former for match figures of eight for 106.
After bowling Essex out for just 94 on Sunday, however, Derbyshire found themselves chasing 346 for victory.
At stumps, they were second favourites on 167 for five after Tymal Mills had taken three for 29.
In a tight match at New Road, Kent's new overseas signing Doug Bollinger took five for 43 on debut against his former club as Worcestershire made 270 in their second innings.
Wicketkeeper Ben Cox top-scored for the Pears with a career-best 89, before Kent - needing 266 for victory - hit early trouble and closed on 51 for three.
Down the M5 at Bristol, Hamish Marshall (84no) kept Gloucestershire in the contest against Hampshire.
The hosts conceced a first-innings deficit of 118 as Hampshire lost their final wicket this morning to Matt Taylor (five for 75) - Adam Wheater for 82 - to be all out for 422.
Alex Gidman then made 72, but Gloucestershire were still struggling until Marshall and tail-ender David Payne shared a stand of 92 in a stumps score of 308 for nine.