Kane Williamson fell short of a century for the second time in the match, the New Zealander adding 97 to his first-innings 84, to end a stand of 264 with Phil Jacques, who swiftly followed for 152.
At lunch the Tykes, who started the match 25.5 points ahead of their main title rivals, were 351 for five but only 52 ahead after following on badly in arrears.
Sussex were also trying to bat their way out of trouble on the last day against Warwickshire and Ed Joyce and Rory Hamilton-Brown were going well at Edgbaston.
Having begun the day 65 ahead at 148 for three, Sussex lost nightwatchman Will Beer for 11 but Joyce (50 not out) and Hamilton-Brown (36no) added an unbroken 54 by lunch.
Derbyshire overhauled Surrey's first-innings lead on the third morning at the Oval.
Ben Slater fell for 13 but Derbyshire took lunch 10 ahead at 80 for one, with Paul Borrington 38 not out.
Division Two leaders Lancashire encountered resistance in their bid to close out victory over Hampshire at Southport.
Chasing a distant 496, Hampshire resumed at a forlorn 137 for seven but reached 282 for no further loss by the interval, with Adam Wheater 117 not out and Matt Coles on 54.
Worcestershire were set 185 to beat Leicestershire, who were bowled out just before lunch for 248.
Ned Eckersley advanced from 91 to 119, his second century of the game, but just 58 runs were added in 22.2 overs as Jack Shantry finished with four for 53 and Shaaiq Choudhry picked up two wickets.
Gloucestershire, chasing an unlikely 432 to beat Essex, were 115 for one with Michael Klinger 38 not out and wicketkeeper Gareth Roderick on 39.