Auqib Nabi, Zain-ul-Hassan claim four each on 20-wicket day

Surrey's Matt Fisher was also forced out with groin injury after taking 2 for 18 from 11 overs

Glamorgan 132 (Nabi 4-36) and 30 for 0 lead Surrey 115 (Zain-ul-Hassan 4 for 26) by 47 runs

Twenty wickets tumbled on an extraordinary opening day at the Kia Oval as Surrey bowled out Glamorgan for 132 but then slid to 115 all out themselves in reply.

Surrey's Matt Fisher was also forced out of this County Championship match with a groin injury, after taking 2 for 18 from 11 overs, and was replaced by James Taylor.

Substitute Taylor found himself both batting and bowling in the final session of the day, with Glamorgan reaching stumps on 30 without loss, a lead of 47, with the last 3.4 scheduled overs lost to bad light.

The seam bowlers from both sides held sway throughout, with 19-year old Jack Hope-Bell top-scoring with 33 for Glamorgan in his second first-class appearance and Ryan Patel's 26 being the best that Surrey could offer.

Zain-ul-Hassan, the 25-year-old Glamorgan opener, batted twice in the day and in between grabbed 4 for 26 with his medium-pacers.

Timm van der Gugten started the Surrey rot, Dom Sibley following an outswinger and edging to first slip. But it was ul-Hassan - with just 39 first-class wickets previously at 47.84 runs each - who accelerated the hosts' decline either side of tea by dismissing Rory Burns, lbw for 20, Ollie Pope for a first-ball duck and Dan Lawrence for 9, squared up and bowled by a beauty.

And 59 for 4 quickly became 68 for 6 as Patel was bowled through the gate by Ray Toole and Adam Thomas bowled off stump by another ul-Hassan leg-cutter.

Tom Lawes tried to counter-attack with 17 but Surrey's trials with the bat were almost complete when they lost three further wickets at 103 - Lawes caught behind off left-armer Mir Hamza, Ben Foakes bowled by Van der Gugten for 19 and Auqib Nabi leg-before to Hamza without scoring.

After a few defiant blows from last man Dan Worrall the innings ended with Taylor bowled through a defensive push at Van der Gugten, who claimed 3 for 31.

Nabi was earlier the pick of Surrey's four-man seam attack with 4 for 36 from his 10 overs while Worrall, Fisher and Lawes took two wickets apiece.

Apart from their batting woes, Surrey saw Fisher limp off the field immediately after having van der Gugten caught at the wicket for a duck with the last ball of a double-wicket maiden in which Mason Crane also edged to second slip.

Opting to bowl first, Surrey would have been slightly disappointed that Glamorgan managed to reach lunch on 93 for 4 on a seaming pitch. Fisher, in particular, was not at his best with the new ball and although Worrall struck in the fifth over, having ul-Hassan leg-before for a tortuous 16-ball duck, Glamorgan then moved reasonably smoothly to 53 for one.

The innings, however, was undermined by Nabi's first spell of 5-2-27-3, the Indian seamer removing Asa Tribe, Kiran Carlson and Hope-Bell in an impressive burst.

Finding some late movement both in the air and off the pitch, Nabi had Tribe taken at second slip for 31 with his seventh ball and, after seeing Sibley cling on to a juggling effort at first slip to remove Carlson for nought two overs later, he produced a superb leg-cutter to hit Hope-Bell's off stump past a forward defensive stroke.

Tribe had played well for his 31, twice clipping Fisher for fours to deep square leg, while Hope-Bell also looked good in his 33, square-cutting Fisher high over cover for four and then repeating the stroke off Lawes and collecting six for it to the short boundary on the Harleyford Road side of the ground.

Glamorgan's innings fell away spectacularly after lunch, with Kelleway held at second slip off Worrall for 22 and then the last five wickets being lost for just 12 runs inside eight overs.

Nabi returned to have Billy Root caught behind for a laboured 11 from 49 balls, the left-hander cutting at a ball too full for the shot, and after Fisher had removed Van der Gugten and Crane in five balls it was Lawes who wrapped things up as Chris Cooke edged to keeper Foakes and Hamza picked out Pope at cover.