Worcestershire captain Daryl Mitchell became the second player to reach 1,000 runs in the current LV= County Championship season before Leicestershire’s bowlers pegged the Division Two leaders back to 317 for nine.
Everything was going well as Mitchell and new partner Richard Oliver made trouble-free progress in an opening stand of 163 at New Road, but there was surprise in store when paceman Nathan Buck led the Leicestershire revival by taking three for one in 11 balls.
Spinners James Sykes and Dan Redfern shared the spoils as the bottom-of-the-table visitors – without a championship win in 26 matches – claimed six wickets for 95 runs between lunch and tea.
Sykes, who took 3-72, added two more in the final session, mostly importantly the lbw dismissal of Tom Kohler-Cadmore for 41 after the teenager steadied Worcestershire in a partnership of 44 in 21 overs with Shaaiq Choudhry.
Choudhry, essentially brought in to fill Moeen Ali’s role as a spin bowler, showed his value as a lower-order batsman with 40 not out from 107 balls and Saeed Ajmal drove Buck for six before he was dislodged by a lifter from Charlie Shreck for 20.
Leicestershire’s team selection suggested they had been reading up on the success enjoyed by Ajmal in taking 41 of his 56 wickets for Worcestershire this season on New Road pitches.
Regular spinner Jigar Naik was given extra support as the Grace Road side brought in Sykes on the back of a match-winning return of 7-80 for the second XI last week, and used Redfern in damaging mini-spells in the afternoon.
Yet the early evidence was that a sluggish first-day surface would produce big rewards for batsmen when Worcestershire won the toss for the fifth time in their six home matches.
Mitchell slipped into a comfortable groove and Oliver, newly promoted to the championship side after a successful introduction in the NatWest T20 Blast team, again made a favourable impression with his positive strokeplay against the seamers.
The 24-year-old left-hander scored 65 on his debut against Glamorgan in the last four-day match and surpassed that with 78 from 94 balls on his second appearance.
Meanwhile, the milestones rolled along for Mitchell, reaching 1,000 for the summer when he had made 54 and 8,000 in his first-class career when on 68.
By lunch the partnership was worth 133 but the day was reshaped from the moment Oliver was given out lbw, attempting to sweep Sykes, after hitting a dozen boundaries.
Leicestershire captain Josh Cobb then came up with something of masterstroke, calling up Redfern for one over in which Mitchell, having hit 11 fours, was caught behind for 90, aiming to cut the former Derbyshire all-rounder.
Redfern was immediately replaced by Buck and the new-ball spearhead quickly slipped into attack mode.
Tom Fell, shouldering arms, and Ben Cox were bowled by deliveries cutting back and in between Alexei Kervezee gave wicketkeeper Niall O’Brien his second catch.
It was a bonus for Leicestershire when Redfern nipped in for a second success, bowling Joe Leach a couple of overs before tea.
Steve Rhodes, Worcestershire's director of cricket, was delighted for Mitchell.
Rhodes said: "The thing about Mitch is he's been a good player for a long period. Now he and Moeen Ali in particular have stood up even more this year.
"It's nice to see that the better players can improve a little bit more."
Ben Smith, Leicestershire's senior coach, said: "From where we sat at lunch in the game, that was a brilliant effort.
"It probably took us a little bit of time to get used to bowling on that type of pitch but once we did and started to hold them and chip away with wickets, it went well. Nathan Buck bowled a brilliant spell before tea."