Matthew Waite made an impressive debut as part of an on-song Worcestershire attack as Leicestershire were dismissed for 148 on the opening day of the LV=Insurance County Championship encounter at New Road.
The on-loan Yorkshire pace bowler came on first change, picked up two wickets and bowled with great accuracy in returning figures of 11-6-15-2.
It was his first senior cricket of the summer, but he and his teammates quickly settled into a groove and constantly asked questions after Leicestershire opted to bat.
Dillon Pennington bowled a particularly impressive opening spell, and then Charlie Morris and Ed Barnard wreaked havoc in taking four wickets for three runs in the space of 32 balls.
Worcestershire claimed maximum bowling points, and then Azhar Ali and Jack Haynes pushed home their advantage as they shared a century partnership for the third successive match.
The duo had shared in stands of 195 versus Durham and 187 against Derbyshire and ended today with the stand so far worth 106.
Azhar (60 not out) completed a fourth successive half-century, and by the close, he and Haynes (42 not out) had lifted the total to 159-2 and a lead of 11 runs.
The home side made two changes from the eleven in action against Derbyshire with Waite and Pennington, fit again after a hamstring injury, replacing Adam Finch and Ben Gibbon.
Leicestershire had a new captain at the helm in Callum Parkinson, who has stepped up from vice-captain to lead the County Championship side for the rest of the season.
Parkinson won the toss and elected to bat, but his side were soon on the back foot against the probing Worcestershire attack.
Hassan Azad (1) survived one confident lbw shout from Pennington, but the next delivery smashed into his pads, and he was given out with nine on the board.
Leicestershire would have been reasonably content to lose only one wicket in the first hour, but then Morris and Barnard wreaked havoc with four wickets between them for just three runs.
Rishi Patel (24) was undone by a delivery from Morris, which stopped on him and popped up a catch to Azhar Ali at short mid-wicket.
Barnard was rewarded for some probing bowling as Colin Ackermann (1) nicked a deliver, which moved away to Ed Pollock at first slip.
Morris struck again when Lewis Hill (23) went leg before to a ball swinging into him, and Wiaan Mulder (0) departed after a brilliant catch by Josh Baker at third slip off Barnard.
Worcestershire made further inroads before lunch as Rehan Ahmed (0) – the 500th player to play first class cricket for Leicestershire went to pull Pennington and top-edged to Pollock at first slip.
Ben Mike (0) survived a chance off Barnard shortly before lunch, and he and Harry Swindells counter-attacked for a period after the resumption before three wickets fell for one run.
Waite was rewarded with two wickets in two overs.
Swindells (23) got in a tangle with a delivery and ballooned the ball onto the offside where Jack Haynes, running across from second slip, took the catch.
Mike (16) played down the wrong line to Waite and was bowled, and then Ed Barnes (1) chopped Josh Baker onto his stumps at 98-9.
Resistance came from the last wicket pair of Parkinson (22) and Chris Wright (27 not out), who added exactly 50.
Barnard claimed his third scalp when Parkinson presented Pollock with his third catch of the innings.
Barnard ended with figures of 14.2-4-45-3, Waite 11-6-15-2, Morris 9-2-31-2, Pennington 14-6-33-2 and Baker 4-2-14-1.
When Worcestershire launched their reply, Pollock was in typically aggressive form with a series of boundaries.
Jake Libby, a century-maker against Derbyshire, also looked in good nick as the
pair put on 48 in 9.3 overs.
Mulder checked their progress when trapping Libby lbw for 17, and he followed it up with the wicket of Pollock (32), who picked out Ed Barnes at deep backward square leg.
But Azhar produced some delightful drives and cut shots, and Haynes also entertained the crowd with some pleasant strokes during the evening sunshine.
Pakistan star Azhar brought up his half-century from 71 balls with six fours.