A half-century from Harvey Hosein and four wickets from Matt Critchley set up a tantalising final day in the Bob Willis Trophy fixture against Lancashire.
Hosein (84) put on 102 for the eighth wicket with Mattie McKiernan (31) as Derbyshire looked to keep their hopes of a place in the Bob Willis Trophy final alive, with the visitors eventually dismissed for 195.
An opening-stand of 138 between Alex Davies (86) and Keaton Jennings (81) built a lead for Lancashire in Liverpool, before six wickets shared between Critchley (4-126) and Luis Reece (2-49) in the final session left the match with all results still possible on the final day.
Lancashire will resume on Day Four on 312-6, leading by 336, with George Balderson unbeaten on 56 and Danny Lamb not out on 16.
Under bright sunshine at Aigburth, Hosein and McKiernan returned to the crease and continued their rebuilding job, one that was not destined to end until well into the first session.
After resuming on 44, Hosein reached 50 from 138 balls, including six fours, before McKiernan was trapped lbw by George Burrows to leave Derbyshire 163-8.
However, the half-centurion was unable to reach three-figures, as he was caught by George Lavelle off Jack Morley, meaning that the final pairing of Sam Conners and Dustin Melton would need 22 runs to reach 200.
Melton cracked a six off Danny Lamb (4-60) on his way to 11, but he was unable to repeat the trick as the paceman bowled him to dismiss Derbyshire for 195, still 24 runs behind.
The Lancashire opening pair of Jennings and Davies each scored their first runs of the match in the second innings, after falling for ducks on the opening morning of the game.
They shook off any fears of a pair, and added 126 runs before tea, moving their lead to 150 runs at the interval, as Derbyshire plugged away in their search for wickets.
Critchley’s 12 dismissals prior to this game made him Derbyshire’s leading wicket-taker in the Bob Willis Trophy, and he added to his tally when he had Davies caught by Anuj Dal shortly after the interval.
The all-rounder then dismissed Jennings to pick up his 150th wicket for Derbyshire across all formats, before removing Rob Jones (5) and Dane Vilas (10), either side of Reece having Josh Bohannon (35) caught by Wayne Madsen.
Reece trapped George Lavelle (7) lbw, as the hosts ended the day on 312-6, leading by 336.
Vitality Blast is back! Derbyshire Falcons return to Twenty20. Follow every game live on our match centre at derbyshireccc.com. Derbyshire Falcons: Underestimated No More.