Luis Reece claimed two late wickets on Day Two as Sussex built a lead at The County Ground.
A century from Cheteshwar Pujara led a Sussex batting display on the second day of the Vitality County Championship Division Two match against Derbyshire.
The Indian maestro scored an unbeaten 104 with Tom Haines, Tom Alsop and James Coles all making half-centuries as Sussex closed on 357 for 5, a lead of 111.
Sussex’s position would have been even better but for two late wickets for Luis Reece to keep Derbyshire in the game.
The home side had earlier taken their first innings to 246 thanks to a career-best 47 from Blair Tickner who shared a ninth-wicket stand of 68 with Jack Morley, before Coles took 2 for 6 with his left-arm spin to finish off the innings.
The cloud cover of the first day was replaced by patches of blue sky, making batting a more comfortable proposition and Tickner and Morley took advantage.
Tickner pulled an Ollie Robinson no ball to the ropes and there was more frustration for the pace bowler when Tom Clark put down a difficult low chance at second slip with Morley on six.
The pair completed a 50 stand from 75 balls and Tickner was in sight of a maiden first-class half century when he made room to force Coles and was bowled by a quicker ball.
Morley had played the supporting role, displaying sound defence, but with Tickner gone, he became more expansive and came down the pitch to dispatch Jack Carson over long on for six.
Derbyshire were closing in on a batting point when Morley used his feet again to try and force Coles through the offside but missed the ball and was stumped.
Although their score was higher than had looked likely when the eighth wicket went down at 163, early wickets were needed to put Sussex under pressure and Daryn Dupavillon obliged in his second over.
The South African fast bowler moved one back in from outside off to bowl Clark but the bowling was too inconsistent and Haines pounced on anything that was slightly offline.
He reached his 50 which came from only 38 balls in the first over after lunch and the stand with Alsop was worth 90 when he played on aiming to cut a ball that was too close to him for the stroke.
The sight of Pujara walking out to bat on a ground where he made a double century two years ago was an ominous one from a Derbyshire point of view and he was soon working the ball around with a quiet assurance.
Alsop reached his 50 with consecutive fours off Luis Reece but two overs before tea, he aimed to work Anuj Dal through midwicket and was lbw.
At the interval, Sussex were trailing by 50 and with Coles playing positively from the start, they began to take a grip on the match in the evening session.
Coles launched Morley over long on for six before Pujara reached 50 from 74 balls, the same number Coles needed to complete his when he pulled Zak Chappell to the fine leg boundary.
The partnership was worth 141 when Coles drove Reece low to mid off and after Pujara punched David Lloyd to the cover boundary for his 10th four to complete a century off 158 balls, Reece bowled John Simpson with one that straightened.
Derbyshire claimed the new ball before the close but Pujara and Jack Carson stood firm to ensure it was the visitors day.
Derbyshire captain David Lloyd said: “I think we bowled better and better as the day went on, after a bit of a leaky start the way the lads ran in and the effort they showed was pretty spot on. On another day we could have had them potentially seven down.
