Greg Smith leaves Derbyshire in charge
Worcestershire 279 and 70 for 3 v Derbyshire 405
Greg Smith made his highest score for nearly two months to give Derbyshire a chance of a first Championship victory since late April at Derby.
Smith made 91 off 163 balls as Derbyshire claimed a first-innings lead of 126 and then reduced Worcestershire to 70 for 3 at the close.
Bangladesh captain Shakib Al Hasan took 3 for 94 but Derbyshire's last five wickets added 168 to take the home side to 405 before their bowlers left the visitors facing defeat.
The match was in the balance at the start of day three with Derbyshire 96 runs behind with six wickets intact but the home side slowly gained the initiative after Worcestershire's bowlers failed to make an early breakthrough.
Smith and Dan Redfern batted through the first 18 overs before Matt Mason finally struck with the new ball when Redfern was well caught at second slip by Daryl Mitchell for 19.
Redfern had faced 110 balls but he had done a valuable job in frustrating the bowlers who were then held up by Smith and Robin Peterson as the sixth-wicket pair put on 71 in 22 overs to take Derbyshire past 300.
Smith had not scored a half century in any form of cricket since late May - against Worcestershire - but he showed his confidence had returned by hammering four boundaries in an over from the wayward Richard Jones.
He looked set for a hundred until he drove Moeen Ali's off-spin loosely to short extra cover and Derbyshire were only 45 runs on when Peterson was caught at short leg to give Shakib his first Worcestershire wicket. But Steffan Jones mixed watchful defence with some punishing blows, including two big sixes over midwicket, to score 40 off 43 balls and Lee Goddard chipped in with 38 to leave Worcestershire with a lot of batting to do.
David Wheeldon had batted for more than three hours for 20 in the first innings and he was again threatening to stand in Derbyshire's way when Jones broke through with the last ball of his second over.
The experienced pace bowler found the outside edge as Wheeldon prodded forward and Goddard pouched the chance to end the opener's one-hour occupation. Worcestershire suffered another blow five overs later when skipper Vikram Solanki got a good ball from Mark Footitt that left him and Chris Rogers dived forward at first slip to hold a fine catch.
Derbyshire's celebrations showed just how important they thought that wicket was and they were gifted a big scalp off the penultimate ball of the day. Mitchell and Moeen had dug in for 14 overs to reduce the arrears to 56 when Moeen drove loosely at Peterson and sliced a catch to point to leave Derbyshire scenting victory.