Glasgow handed defending champions Ospreys their third successive RaboDirect PRO12 defeat with a 28-10 victory in their clash at the Liberty Stadium in Friday night.

DTH van der Merwe scored two tries to help the visitors register their first win of the campaign with flanker Chris Fusaro also crossing with outside-half Duncan Weir adding 10 points with the boot. The Ospreys' only try came from lock Ian Evans with the result marking the Welsh region's worst start to a season since 2007

With nine players injured, including Ryan Jones, Adam Jones and Eli Walker, the Ospreys gave a first start in the Pro12 to wing Tom Grabham. For the Warriors, who had previously lost to Ulster and Scarlets, there was a late re-jig to their back-row with James Eddie drafted in at blindside flank and John Barclay replacing Ryan Wilson at No.8.

The Ospreys started on the front foot but blanket Glasgow defence forced Dan Biggar to launch an up and under, except Van der Merwe caught the ball and sprinted 70 metres for the opening try on three minutes. Weir failed with the conversion and then was wayward with a 45-metre penalty attempt three minutes later.

Scrum-half Chris Cusiter earned a penalty for Glasgow which Weir kicked to extend the visitors' lead to 8-0, but it came at a cost to Cusiter, who was forced off with an arm injury to be replaced by Henry Pyrgos. With the Ospreys struggling at the set pieces, Glasgow manoeuvred themselves into a couple of try-scoring positions in the second quarter but could not finish them off.

But they did get a second try on 28 minutes when Fusaro pounced on a loose ball and went in at the left corner after Ospreys scrum-half Rhys Webb fumbled a ball at the base of a ruck. Weir converted to give Glasgow a 15-0 lead. At the other end the Ospreys, plainly low in confidence, butchered an attack in the dying seconds of the half.

The Ospreys tried to get a positive attack going after the interval but were penalised in the Glasgow 22 and Webb was then yellow-carded for a professional foul which allowed Weir to put over his second penalty as the Scots extended their lead to 18-0 on 46 minutes.

Both sides were reduced to 14 when Eddie was sin-binned as the Ospreys pressurised the Glasgow line, which the home side eventually breached when Evans crashed over on 51 minutes, a try converted by Biggar.

But the Ospreys comeback lasted only three minutes before Van der Merwe crashed over for his second try, converted by Weir. Five minutes from time replacement Ruaridh Jackson confirmed the Warriors' win with a penalty after more Ospreys indiscipline.