Essex leg-spinner Danish Kaneria took seven for 111 and Glamorgan opener Gareth Rees scored a century as the two promotion hopefuls shared the honours on the first day at Cardiff.

Glamorgan finished the day bowled out for 311 with Rees having made 122.

After winning a useful toss Glamorgan, who made three changes from the side that drew with Leicestershire, made a positive start aided by an attacking half century from Australian left hander Mark Cosgrove.

He drove effectively as Glamorgan reached 70 for nought in the first hour before Kaneria was drafted into the attack.

But Cosgrove refused to be tied down and went to a 57-ball half century by chipping Kaneria for a straight six.

However, four overs later Cosgrove perished when he was bowled by Graham Napier from around the wicket leaving Glamorgan 98 for one.

That was 99 for two an over later with Will Bragg adjudged leg before by umpire David Millns to only the third ball he faced from Kaneria.

After reaching lunch at 112 for two, Glamorgan continued steady progress with Gareth Rees having laid anchor.

But Kaneria struck for a second time when Michael Powell got a leading edge and was caught at mid-on by David Masters.

The fourth-wicket partnership between Rees and skipper Jamie Dalrymple settled the Welsh county down with the 200 coming up in the 57th over courtesy of a six by Dalrymple off Tim Phillips.

But Kaneria's decision to change ends proved a fruitful one as he broke through twice in the space of three overs.

First he produced an impressive leg-spinner which bowled Dalrymple through his legs ending a 71-run partnership with Rees.

And then a googly undid Jim Allenby who chopped onto his stumps as Glamorgan reached tea at 228 for five.

Shortly after tea Kaneria completed a burst of three wickets in 20 balls when he had Mark Wallace stumped three yards out of his ground.

The Pakistan Test star thought he had a sixth wicket when Rees was given out leg before by George Sharp, but before the opener had crossed the rope he was called back after the umpire reversed his decision.

It allowed Rees to extend his seventh-wicket partnership with Robert Croft to 52 before the off spinner was caught behind off Masters.

Rees was eventually bowled via a bottom edge ending a near six-hour innings having faced 245 balls.

Kaneria struck twice again to dismiss Dean Cosker and Garnett Kruger before the end.