Derbyshire 198 for 6 (Godleman 54, Patterson 3-16) trail Yorkshire 400 for 6 declared (Malan 219, Tattersall 66) by 202 runs
Home debutant Dawid Malan completed a superb maiden career double hundred before watching Derbyshire battle to within touching distance of the follow-on target of 201 at Emerald Headingley.
Malan's 219 off 244 balls underpinned the White Rose's first-innings 400 for 6 declared, achieved shortly before lunch on day three of this weather-affected North Group fixture.
Derbyshire captain Billy Godleman's 54 then led his side's bid to avoid having to follow-on, something which would go a long way to securing an important draw against their fellow challengers.
The visitors closed on 198 for 6 from 70 overs, with bad light ending play three overs early. Almost 100 overs have now been lost across three days.
The gap between these two leading sides in the North was four points before this third-round clash, with Derby leading the way.
England T20 batsman Malan, who could be playing his last county game until mid September should he be involved in forthcoming series against Pakistan and Australia, advanced from 153 not out overnight.
He became the first Yorkshire player whose maiden century for the club ended up a double since Jonny Bairstow hit 205 against Nottinghamshire in 2011.
The 32-year-old was the primary reason why Yorkshire secured the maximum five batting bonus points for reaching 400. Derby claimed two bowling points.
The hosts scored 112 runs in 22.1 overs before lunch, with Malan moving to - and beyond - 200 with two fours and two sixes off Leus du Plooy's part-time left-arm spin before falling caught at long-off trying to hit a third successive six.
He completed a 200-run stand with Jonny Tattersall (66) - a fifth-wicket record for Yorkshire in first-class matches against Derbyshire.
Tattersall chipped leg-spinner Matt Critchley to cover before Malan, who batted serenely in especially challenging conditions during Saturday's opening day, fell 89 runs later.
All-rounder Jordan Thompson added an unbeaten 36 before striking with the ball during the afternoon when Derbyshire lost their first two wickets on 58.
Godleman and fellow opener Tom Wood united either side of lunch before the latter was caught and bowled by Thompson in the 18th over.
Excellent Steve Patterson then trapped Wayne Madsen lbw for a duck before Godleman and du Plooy shared 68 for the third wicket.
However, both fell in the space of four balls to Patterson across two overs after tea as Derby slipped to 127 for 4 to give the hosts an opening. Du Plooy was caught low down at first slip by Tom Kohler-Cadmore and Godleman caught behind by Bairstow.
Patterson finished with figures of 3 for 16 from 16 overs.
Dom Leech had Alex Hughes caught at mid-on by Duanne Olivier following a miscued pull, and Olivier added the wicket of Harvey Hosein, expertly caught behind by a diving Bairstow five overs later with the score on 174.
Critchley finished the day unbeaten on 31, with Anuj Dal on 15, as the pair took their side close to a position of safety.
