Joe Leach maintained his superb form with the ball as Worcestershire's bowlers struck back after Joe Clarke had scored his maiden first LV = County Championship half century in the derby clash with Warwickshire at New Road.
Leach took his wicket tally to 30 in his fifth Championship appearance of the summer with a three wicket blast.
He dismissed Warwickshire openers Varun Chopra and Ateeq Javid plus Laurie Evans during an opening spell of 3-18 from nine overs.
Jack Shantry weighed in with the wicket of Jonathan Trott as Warwickshire were reduced to 35-4 in reply to Worcestershire's 243 all out before eventually closing on 101-4 from 30 overs.
The highlight of the Worcestershire innings was the performance of Clarke in only his second Championship appearance.
The England Under-19 wicket-keeper went to his fifty off 58 balls with nine fours before being dismissed by Boyd Rankin without addition to his tally.
Clarke, the only player to ever score two double hundreds for the county's second eleven, came in at 124-4 and was eighth out at 225.
It was another sign of the great promise of Clarke and fellow Under-19 player Ed Barnard who has also broken into the first team this season.
Clarke, 19, shared in a sixth wicket stand of 53 in nine overs with Leach.
But wickets fell steadily during the afternoon session and Worcestershire, who were 104-1 shortly before lunch, were dismissed for 243 in the 66th over.
Mitchell won the toss and elected to bat with the home side making two changes from the side which drew with Hampshire at the Ageas Bowl.
Moeen Ali and Saeed Ajmal came into the side in place of Colin Munro and Barnard.
Keith Barker opened the bowling at the Diglis End and began with a maiden to Mitchell who got off the mark with an off drive for four off Chris Wright.
Richard Oliver looked in good form, clipping Wright off his legs for four and on driving the same bowler for three.
A power cover drive to the ropes off Barker took the left hander into the 20s.
Oliver moved onto 27 from 23 balls but was then adjudged to have edged a delivery from Wright through to keeper Tim Ambrose with 38 on the board in the ninth over.
His dismissal brought in Moeen Ali to warm applause for his third Championship appearance of the campaign.
The England all-rounder looked in good touch and a delightful cover drive for four from Wright got him off the mark as the 50 came up in the 13th over.
Moeen then collected three boundaries in an over from Wright via an on drive and two off drives.
A double bowling change saw Rikki Clarke and Boyd Rankin come into the attack and Mitchell cover-drove the pair for boundaries.
The 50 partnership between Mitchell and Moeen came up in 14 overs before spin was introduced for the first time with Jeetan Patel at 96-1 after 25 overs.
The second wicket pair continued to score freely until Mitchell's dismissal in the final over before lunch for a patient 36 from 95 balls with seven fours.
The 31-year-old clipped a delivery off his legs from Wright into the hands of Ateeq Javid at mid wicket.
Worcestershire resumed after lunch on 104-2 and Tom Fell got off the mark with an on drive for four off Barker.
But it was his only scoring stroke before he tried to leave a delivery from the same bowler and was bowled via the inside edge.
Alex Gidman opened his account with an impressive shot off his legs at Wright's expense but from the next ball was caught down by leg side by Ambrose.
Moeen moved onto 45 in assured fashion but he fell in a similar fashion to Mitchell as Javid held the catch at mid-wicket off Barker.
Clarke and Leach led a partial recovery during a partnership of 53 in nine overs.
Clarke straight drove Wright for four and brought up the 150 with a flick down the legside for four off Barker.
Leach pulled Rankin for six but the bowler switched ends and dismissed the all-rounder on 22 after he went for a pull and was caught and bowled.
Clarke collected three boundaries in an over from namesake Rikki Clarke via a cut, pull and thick edge to third man.
There was a rare failure from the in form Ben Cox who was adjudged lbw for three after pushing forward to Jeetan Patel.
Clarke secured the first Worcestershire batting point with a leg glance for four off Patel and then Jack Shantry hammered Rankin over extra cover for six.
There was warm applause when Clarke went to his half century off 58 balls with a single off Rankin before the England paceman dismissed him in his next over,caught at deep square leg by Jonathan Trott.
Ajmal on drove Barker for four before he was caught behind off the paceman for 10 at 238-9.
The innings ended and tea was taken when Shantry was adjudged lbw for 17 to give Barker his fourth wicket.
Leach shared the new ball with Charlie Morris and Chopra on six edged the latter just short of Fell at third slip.
But Leach broke through when Javid (9) was trapped lbw and then Chopra (9) departed in the same manner.
It became 34-3 when Trott (0) pushed hard at a Shantry delivery and Gidman pouched the chance at first slip.
Only one run was added to the total before Evans (1) fell to a fine catch at mid wicket by Oliver to give Leach his third success.
Ian Bell and Tim Ambrose then posted a half century stand in 10 overs.
