Worcestershire paceman Charlie Morris picked up the 100th first class wicket of his career during an afternoon spell of 3-4 in 12 balls as Nottinghamshire were bowled out for 240 at Trent Bridge.
Then openers Daryl Mitchell and Richard Oliver gave Worcestershire a solid start with the latter hitting a 91 ball half century before they closed on 89-2.
Morris went to the personal milestone in his 32nd match when Samit Patel (10) was caught at third slip by last week's century-maker Tom Fell.
He then followed that up with the wickets of wicket-keeper Chris Read (5) and Brett Hutton (0) in the space of three balls.
It was part of a quickfire turnaround in fortunes for Worcestershire who had bowled well in the morning session but had been rewarded with only two wickets after skipper Mitchell put the home side into bat.
Joe Leach and Jack Shantry were also as accurate and probing as ever with two wickets apiece.
Notts were indebted to a half century from opener Brendan Taylor and then a last wicket stand of 50 between Riki Wessels and Andy Carter.
It was Morris and Leach who shared the new ball and they were unfortunate not to pick up an early wicket.
Leach had Brendan Taylor dropped in the gully whilst Morris regularly induced false strokes and beat the outside edge.
But Notts passed 50 in the 11th over, and continued to score at more than four an over until Shantry dismissed Michael Lumb, for 26.
He was undone by a ball which stopped in the wicket and Joe Clarke held the catch at mid wicket with 74 on the board.
Brendan Taylor played and missed at Ed Barnard and then a false stroke brought him to third man and the completion of his 50 from 66 balls with six fours.
Leach came back into the attack 20 minutes before lunch and struck when Alex Hales, who had a loan spell at New Road last summer, did not offer a shot and was bowled for 15 to leave Notts on 98-2 in the 27th over.
They added four more runs before lunch but wickets started to tumble after the resumption.
Leach enjoyed a second success when James Taylor (8) tried to work the ball to leg and was adjudged lbw.
Rikki Wessels was fortunate to edge Leach in between Mitchell and Tom fell at second and third slip for four.
But Shantry ended Brendan Taylor's knock on 69 – from 120 balls with nine fours – when a top edge was held onto by Barnard at mid off.
Morris stayed out of the attack for three overs but soon was amongst the wickets on his return.
He had dismissed Patel twice when playing for Oxford MCCU against Notts last season and the England one-day player became his 100th first class victim.
Morris then dismissed fit again Read (5) who fell to an excellent catch diving away to his right by Ben Cox – in front of England wicket-keeping coach Bruce French – and the same combination accounted for Hutton (0) two balls later.
Barnard got in on the wicket-taking act when Ben Hilfenhaus (0) nicked through to Alex Gidman at first slip at 170-8.
Then a superb throw from the deep by Barnard ran out Luke Fletcher (5) as he was attempting a third run off Morris after Wessels had clipped the ball on the leg side.
Wessels and Carter went on the offensive and the former went to his half century off 81 balls as he pulled Morris for his sixth four.
The 10th wicket pair added 50 in seven overs – and delayed tea – before Saeed Ajmal, introduced into the attack after 65 overs, had Wessels (65) caught off a skier by Fell at deep mid wicket to leave Carter unbeaten on a career best 24.
When Worcestershire launched their reply, Oliver collected the first boundary with a straight drive off Hilfenhaus.
Mitchell had a let off on nine against Hutton wen Hales spilled a chance at second slip before guiding Carter for four down to third man.
Oliver brought the 50 up with a four through backward square leg off Carter in an over costing 14 runs.
Worcestershire looked set to go through the session without losing a wicket until Hilfenhause struck twice in the closing stages.
Mitchell (25) was adjudged lbw with the total on 87 and from the last ball of the day Morris was bowled for a single.
In between Oliver had time to drive Patel for four to reach his half century with his seventh boundary and he ended unbeaten on 52.
It was a welcome tonic for the opener who passed 50 for the first time since his century against Sussex at Hove.
Notts suffered a double injury setback with Fletcher, after three overs, and Carter, with one ball of an over remaining, having to leave the field with injuries.