Promotion favourites Worcestershire endured one of their worst days of the summer in the LV= County Championship as they were dismissed for 194 by Gloucestershire on a seaming surface at New Road.
Having come into the match with a game in hand and 43 points ahead of second-placed Surrey, they are already looking at a sizeable deficit after the visitors' smooth progress to 181-2.
Gloucestershire briefly wobbled at the start, slipping to 43-2 when Will Tavare (23) was caught in the slips off Charlie Morris' second delivery, but Gareth Roderick seized the initiative, adding a fluent and substantial half-century to five catches behind the wicket.
The South African cruised to 88 not out with 15 fours off 107 balls and so far he has put on 138 with Alex Gidman, unbeaten on 57, in cutting the gap to a mere 13 after a day when most things went right for their side.
Earlier in the day, with the ball consistently moving about off the seam, Craig Miles led the assault on Worcestershire with 4-54 and the other wickets were equally shared by Liam Norwell and Benny Howell.
In Swansea, Jim Allenby produced figures of 5-56 as Glamorgan enjoyed the better of the opening day of their LV= County Championship Division Two clash with Essex.
The all-rounder took three wickets in the space of five overs and then mopped up the tail as Essex lost their last six wickets for the addition of only 66 runs.
Essex were bowled out for 286, with the main contributions coming from openers Tom Westley and Nick Browne, who made 60 and 73 respectively.
In reply, Glamorgan finished the first day on 27-1, 259 behind, having lost Will Bragg to a catch behind off Monty Panesar two overs from the close. That brought nightwatchman Andrew Salter to the middle.
Steven Davies scored his second LV= County Championship century of the season and Vikram Solanki hit 93 as promotion-seeking Surrey took control of their Division Two game against bottom-of-the-table Leicestershire at Grace Road.
Put into bat on a green-looking pitch, Surrey recovered from a shaky start to post an imposing total of 403-8 when bad light ended play half an hour early.
Davies was still there unbeaten on 147 off 168 balls having struck 22 fours off the toiling Leicestershire attack.
It was a boundary-laden day with a total of one six and 61 fours helping Surrey race to maximum batting points.
Yet it had looked a good toss to win with conditions seemingly favouring the bowlers and in the fourth Nathan Buck produced the perfect delivery to dismiss Zafar Ansari, but Leicestershire were initially unable to build on their fine start as Surrey’s innings gathered momentum.
Sean Ervine made the best of a placid Canterbury pitch to ease Hampshire into the driving seat on the opening day of their LV= County Championship Division Two clash with Kent.
The 31-year-old Zimbabwean scored an unbeaten 75 from 110 balls to resurrect a Hampshire innings that, at 187-5, had threatened to seriously underachieve.
Mitch Claydon, bowling with a 1914 half-crown in commemoration of the First World War, found the inside edge of Jimmy Adams’ bat with the first ball back from a rain break before James Vince and Will Smith (56) also went to join opener Michael Carberry (39) in the dressing room.
Liam Dawson (36) nicked a fourth catch to Billings to make it 187-5 but Ervine, resolute and punishing when anything short was on offer, stroked six boundaries on his way to a 59-ball 50.
With Chris Wood adding 61 from number eight, the visitors recovered to reach 343-7 at the close.