WORCESTERSHIRE skipper Daryl Mitchell registered his fifth century of the season on a see-saw opening day in the LV= County Championship clash with Gloucestershire at Cheltenham.

The 30-year-old opener reached three figures off 223 balls with 13 fours after winning the toss and electing to bat as his golden summer continued.

Richard Oliver and Ben Cox also chipped in with aggressive half-centuries for the unbeaten Division Two leaders during partnerships of 71 and 102 respectively with Mitchell.

But, in between, wickets fell cheaply as Worcestershire closed on 299-7 from 96 overs.

They were given a flying start by Oliver, who continued the good form shown in his opening two Championship matches with Glamorgan and Leicestershire.

He peppered the boundary boards in the opening overs and, when the 50 came up, the former Shropshire captain had scored 44 of them.

Oliver raced to his half-century - his third in five innings - off only 42 balls with seven fours.

But, after making 62 out of 71, Oliver fell to a sharp catch at second slip by former Worcestershire player Michael Klinger off Craig Miles (4-53), who was making his first appearance of the campaign.

Mitchell was joined by Tom Fell and the duo took Worcestershire through to lunch at 118-1 - but two wickets quickly fell after the interval.

First, Fell was trapped lbw by Miles for 24 in his first over after the resumption and then Alexei Kervezee (7) used his feet to spinner Tom Smith but was caught and bowled.

It became 140-4 when Tom Kohler-Cadmore, who fell one short of his maiden Championship century against Leicestershire, was stumped by Adam Rouse off Smith (3-68).

Worcestershire needed to rebuild and Mitchell dug in while Cox played a typically fluent innings.

The Worcestershire wicket-keeper was quickly into his stride with a cover-drive for four off Smith.

Mitchell, who passed 1,000 runs for the season last week, reached his half-century off 124 balls with eight fours.

Cox pulled and drove Liam Norwell for two fours in an over as the 50 stand came up in 12 overs.

He went to his 50 off only 58 balls with the aid of seven fours and a six out of 221-4 in the 59th over.

By tea the stand had been extended to 88 out of 228-4 off 65 overs with Mitchell on 69 and Cox 54.

But the game took another twist at the start of the final session with the loss of two quick wickets.

Mitchell and Cox extended their stand to 102 in 28 overs before the latter, on 56, was taken at forward short leg off Smith.

Then, in the next over, Joe Leach, who scored his maiden Championship century at Cheltenham 12 months ago, was adjudged lbw for nought from a full length delivery by Miles to leave Worcestershire on 243-6.

Mitchell cut Smith for four to move into the 90s but then Shaaiq Choudhry (21) pulled Miles straight to mid wicket after adding 38 in 20 overs with the skipper.

A single off Miles took Mitchell to his 100.