Wayne Madsen made a defiant half-century but late wickets put Sussex in charge of their LV= County Championship match at Derby.
Shivnarine Chanderpaul, making his 300th first-class appearance, struggled for 87 minutes for 20 before he fell to Australian paceman Steve Magoffin and with Derby skipper Madsen falling for 63 just before stumps, the hosts were 158 for six at the end of a day when 40 overs were lost to the weather.
After so much rain overnight and during the morning, it was no surprise when Sussex captain Ed Joyce put Derbyshire in on a green pitch after Madsen lost the toss for the sixth time this season.
There was bad news for the home side before a ball had been bowled, with key batsman Wes Durston ruled out with a back injury, while Magoffin returned to the Sussex side after missing the previous game with a sore knee.
Chesney Hughes (15) hooked James Anyon over square leg and into a communal garden early on but then tried to drive Magoffin and edged high to third slip, where Joyce took a sharp catch above his head.
Madsen joined Billy Godleman and they took the total to 71 before Godleman (26) lost patience and chased a wide ball from Chris Jordan and Luke Wells at second slip made no mistake.
Chanderpaul joined Madsen to take Derbyshire to 94 for two at tea but drove tamely to substitute fielder Andy Miller at short extra-cover when on 20.
Dan Redfern took a painful blow in the box from Anyon and two balls later he was lbw playing across the line to leave his team in trouble on 128 for four.
It was important for Derbyshire that Madsen remained but he got a vicious lifter from Jordan and was caught behind after 196 minutes at the crease.
Monty Panesar then trapped nightwatchman Ally Evans lbw with what was the last ball of a day that had swung Sussex's way.