Sussex 276 for 9 (Philander 69*, Finch 61) trail Leicestershire 340 (Cosgrove 128, Archer 5-67) by 64 runs
An unbroken last wicket partnership of 75 between Vernon Philander and Danny Briggs frustrated Leicestershire after the Foxes had looked set to take a big first innings lead on the second day of their championship match against Sussex.
Australian seamer Clint McKay took four wickets as Leicestershire reduced the visitors to 201-9, replying to the home team's first innings 340.
But Philander, playing his last match for Sussex before returning to South Africa, hit a fine half-century, and Briggs gave him impressively determined support before bad light saw play end with 7.2 overs remaining in the day.
Sussex had been under pressure from the start of their innings, after Zak Chappell bowled acting captain Chris Nash with a delivery which seamed back in to the right-hander, as well as keeping a touch low.
McKay then won two leg before decisions in as many balls, Luke Wells with a delivery which would have gone on to hit off-stump, and Stiaan van Zyl on the back foot to a ball that would have hit middle.
Luke Wright and Harry Finch had added 65 for the fourth wicket before Wright, who had hit eight fours in going to 36, tried to pull a delivery from Ben Raine which also kept low, and lost his off-stump.
The bounce was becoming increasingly unpredictable, and Michael Burgess, formerly of Leicestershire, never looked comfortable before going leg before to McKay.
Finch, who had battled his way through to a half-century, was bowled by a Raine delivery that straightened to hit the top of off-stump, and David Wiese, having been bowled by a Chappell no-ball, could not make the most of his reprieve, edging another Chappell delivery to wicket-keeper Ned Eckersley.
Chris Jordan was fortunate to edge McKay just short of Paul Horton at first slip, but the all-rounder began to settle and with Philander, took the visitors to within reach of the follow-on target of 191 at tea. Shortly after the break, however, Jordan drove at McKay without getting to the pitch of the ball and was brilliantly caught by Tom Wells diving to his left at cover.
Jofra Archer hooked a Dieter Klein bouncer straight to Mark Pettini at deep square leg, but Philander and Briggs played with rather more restraint in seeing their side through a further 25 overs before play ended.
Earlier the Foxes had lost their last three wickets in adding just 18 to their overnight score of 322-7. Chris Jordan, wicket-less on the first day, had Chappell caught off at mid-off by Nash off a leading edge before McKay wafted outside off-stump to give Michael Burgess a simple catch behind the stumps.
Having pulled Jordan dismissively to the midwicket boundary, Mark Cosgrove, on 128, then failed to clear mid-off with an attempted lofted drive.