Billy Godleman hit 122 and there were half-centuries for Wayne Madsen (72) and Alex Hughes (60 not out) as Derbyshre enjoyed a good day with the bat at The 1st Central County Ground.
The opener batted resolutely for his first century of the campaign, with able support from the middle-order as Derbyshire closed Day Two on 315-5, trailing Sussex’s first innings total by 125 runs.
The hosts resumed on 400-7 and Lockie Ferguson took two wickets in as many overs as Derbyshire looked to wrap the innings up quickly, his pace proving too much first for Jofra Archer (15) then David Wiese (93).
Hardus Viljoen bowled Ollie Robinson with a yorker to end a last-wicket stand of 31 and dismiss the hosts for 440, a commanding total but one which was reined in by Derbyshire on Day Two.
The Derbyshire openers safely negotiated their first ten overs to reach lunch unscathed on 52-0 to round off a good morning session.
Ben Slater fell for 24 not long after the interval, caught in the cordon off Robinson, but Godleman and Madsen pressed on with plenty of aggressive intent as the run rate remained around five runs per over.
The opener reached his half-century as Derbyshire past 100, before a quick-fire 50 off 42 balls with 10 fours from Madsen saw the visitors surpass 150 and get a real foothold in the match after being faced with early pressure.
A highly experienced duo, Godleman and Madsen took Derbyshire to 200-1 at tea, but the latter fell to the first Chris Jordan delivery after the resumption.
Godleman was dropped on 92 and Sussex’s chance of having two fresh batsmen at the crease faded as the captain reached his century with the score 217-2 and Alex Hughes also began to settle.
The run rate slowed, but the pair batted well for their 85-run stand which was eventually ended by the leg spin of Luke Wells, who bowled Godleman for a fine 122.
Sean Ervine came and went for 2 after a mix-up led to a run out and night watchman Viljoen was bowled for 13 as Derbyshire ended a productive day on 315-5, trailing by 125 heading into Day Three.
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