Worcestershire trail Derbyshire by 341 runs
Matt Mason followed up his eight-wicket match-winning haul against Gloucestershire last weekend with five for 49 from 20.2 overs as Champion-ship cricket returned to the lovely tree-lined Queen's Park ground here for the first time since 1998.
The right-arm opening bowler dismissed the danger-ous Michael Di Venuto early before snaring Derbyshire's highest-scoring batsmen but the home side, who won the toss in the Division Two fixture on a sweltering day, reached 351all out in the 98th over.
In an awkward four overs to negotiate to the close, Worcestershire openers Stephen Moore and Lou Vincent survived to reach ten without loss.
Derbyshire had the recalled Ant Botha to thank for their first-innings effort after he scored 87, having survived a dropped catch by wicketkeeper Steven Davies when on four. Botha edged the first ball after lunch from orthodox left-arm spinner Ray Price but Davies put down an easy chance.
Derbyshire recovered from 176 for six as Botha combined with former Worcestershire wicketkeeper Jamie Pipe, who scored 46, in a stand of 83 in 25 overs.
Derbyshire's position in the town with the crooked spire had not looked so good when they lost both openers in the first ten overs. Steve Stubbings was run out by a direct hit from mid-wicket and Di Venuto was leg-before wicket to Mason playing no stroke. Chris Taylor and Marcus North took the total to 100 before North tried to hit Price over the top and was well caught at deep mid-on by Roger Sillence.
Price then lured Taylor down the pitch two overs before lunch to have him stumped for 40 but that missed catch straight after the restart proved crucial.
Mason had Hassan Adnan taken at second slip by Graeme Hick before Graeme Welch edged Gareth Batty to the same fieldsman at slip but Botha, who had been left out of the two previous matches, and Pipe began a recovery that was continued by the rest of the lower order.
Mason bowled Pipe but Botha and Graham Wagg added 71 in 18 overs to give Derbyshire the initiative. Botha and faced 166 balls and hit 12 fours before he was caught behind down the leg side off Mason.
With the forecasted thunderstorms failing to material-ise, Derbyshire's chief executive Tom Sears said of the first day back at Chesterfield: "It could not have gone better for us.
"From an operational point of view it's been fantastic."