Keith Barker sliced through the Hampshire top order with a five-wicket haul to give Warwickshire the upper hand on the opening day of the Specsavers County Championship season at the Ageas Bowl.

Barker ended the day with figures of five for 44 before Hampshire pegged the Bears back through a patient rearguard knock by Ryan McLaren.

The 33-year-old South African contributed an unbeaten 84 from 147 balls to lift the hosts to 189 for eight.

The seamer was given the best possible start on a green tinged swinging pitch when, under the new regulations, Ian Bell was able to elect to bowl without a toss.

And he rewarded his captain with a wicket with his 13th delivery, a beautiful ball which caught the edge of Michael Carberry's bat before stinging Tim Ambrose's gloves.

Just five deliveries later the same combination came together to see off young opener Tom Alsop, who tickled an inside edge through to the wicketkeeper.

Barker notched his third of a ferocious opening spell from the Hotel End with Will Smith tapping straight to Sam Hain at short-leg.

Ireland international Boyd Rankin then found James Vince mistiming a leading edge to Hain in the covers.

Barker completed his haul with the wickets of Liam Dawson and Sean Ervine - both leg before - to leave the hosts struggling at 66 for six at lunch.

But McLaren led a fight back for the hosts with a stout half-century coming off 88 balls, but was helped by genuine tailenders Reece Topley and James Tomlinson - once Adam Wheater had been given out leg before to Rikki Clarke.

McLaren and Topley, a winter recruit from Essex, put on a watchful 51 to build a platform.

Topley departed for a first-class best of 15, beating his previous high of 12, when he was comprehensively bowled by England bowler Chris Woakes.

But Tomlinson continued where Topley left off with an unbeaten stand of 51 - although the Hampshire man was given two life lines.

Firstly he was dropped by a sloppy Jeetan Patel at second slip before Varun Chopra put down a sharp chance at gully in the next over - both with the batsman on 12.

Dark clouds and imminent rain called an early end to the first day of the season, with Hampshire 11 runs shy of an unlikely batting point.

Barker said: "It was a brilliant start for me, I couldn't have asked for anything better.

"The lads have bowled really well and stayed in there. We have scrapped quite a bit and they made it quite difficult for us towards the end of the day.

"But we would have taken that score before the start of the day, things are looking good."

On the toss, he added: "We didn't know what to expect. A couple of lads saw the wicket yesterday and thought possibly it would be a bowling day. But it took until we saw the wicket ourselves until we decided what to do."