Wayne Madsen led the way with 111 as Derbyshire laid a strong foundation in their bid to claim a first win of the season in the LV= Insurance County Championship.
The 37-year-old scored his first century of the season and Matt Critchley 85 as Derbyshire made good first use of a flat pitch at Hove against Sussex, reaching 371 for five on day one.
After captain Billy Godleman and Harry Came put on 89 in 16 overs – Derbyshire’s best opening stand of the season – seamer Henry Crocombe picked up two wickets in successive overs to check Derbyshire’s progress.
Sussex had wasted the new ball by leaking seven runs an over in the first hour before Crocombe, one of eight bowlers used, returned for a second spell and struck his third ball, slanting one across to win an lbw verdict after Came made 45.
In his next over Crocombe persuaded Leus du Plooy to clip a length ball low to mid-wicket – du Plooy’s eighth duck of the season – to leave Derbyshire 89 for two.
Madsen and Godleman added 96 in 25 overs either side of lunch and reached their half-centuries in successive overs before Jamie Atkins, the 19-year-old highly-rated quick bowler, marked his return after nearly three months out with shoulder trouble by producing the ball of the day, a lifter which squared up Godleman (52).
But in his 200th first-class match Madsen played with increasing authority and either side of tea he was joined by Critchley in a stand of 123 in 38 overs.
Critchley skipped down the pitch twice in an over to deposit off-spinner Jack Carson over long-on on his way to an eighth half-century of the summer shortly before Madsen eased to the 32nd first-class century of his career.
He had moved onto 111 – his first hundred against Sussex – when left-armer Sean Hunt took the new ball and Madsen swung the second delivery with it to deep square-leg after just over four hours at the crease, during which he faced 182 balls and hit ten fours.
Critchley looked certain to follow Madsen to a hundred only to be bowled off an inside edge by the persevering Atkins for 85 from 152 balls, leaving him needing 15 runs in the second innings to reach 1,000 for the season.