Jonathan Trott survived a barrage of short balls after Sussex had made two early breakthroughs before tea at Hove.
Trott arrived at the crease with Warwickshire on 30-2 after Steve Magoffin and Lewis Hatchett had struck with the new ball.
The former England batsman was greeted with a succession of bouncers from Chris Jordan in particular but reached tea unbeaten on 26 to guide Warwickshire to 73-2 in reply to Sussex's 413 all out.
Trott had one close shave when Steffan Piolet thought he had Trott caught behind but umpire Alex Wharf was unmoved.
Varun Chopra was also fortunate not to be run out by Luke Wells on 23 as he moved to 29 not out.
The afternoon session had started with a flurry of wickets as Sussex slipped from 407-8 at lunch to 413 all out.
Ben Brown fell two short of his half century when he was trapped lbw by Boyd Rankin who bowled Lewis Hatchett two balls later.
Magoffin had Ian Westwood caught at first slip for two in his third over with a ball which bounced sharply off a length and then Hatchett strangled Will Porterfield down the leg side for 12.