Ulster's patchy form continued as they turned in an uninspiring display and sank to a 17-9 defeat away to Glasgow in the RaboDirect Pro12.

The home side's fifth consecutive league victory was secured thanks to 12 points from the boot of Duncan Weir and a Troy Nathan try.

Ulster's nine points came via three penalties from fly-half Ian Humphreys, but they were left with no reward for their efforts as the hosts snatched the win in the closing stages.

Weir broke the deadlock with an early penalty as, despite the omission of second row Richie Weir from their starting XV, Glasgow dominated the opening lineout exchanges.

Ulster, however, looked lively on the counter and Irish international Andrew Trimble made a clean break in midfield before offloading to Simon Danielli.

The Scot was stopped just short however and then penalised for holding on in the tackle.

The scores were level moments later though, as Humphreys slotted a penalty from 30 metres.

It was not long until the relentless forward power of Glasgow paid dividends, a thrusting run from temporary blood replacement Chris Fusaro only being halted by a dangerously high tackle from hooker Andy Kyriacou.

Weir converted the resulting penalty with ease and extended his side's lead further with another successful kick despite the swirling wind.

Humphreys was not so accurate just before half-time, but made amends minutes into the second half after the Glasgow front row were penalised for dropping their bind.

The scores were level again when a kick ahead from Humphreys ricocheted off the foot of Glasgow winger David Lemi.

The ball was gathered by Graeme Morrision but the centre was adjudged to have been in an offside position, allowing Humphreys to slot another penalty.

However, as the wind continued to whistle through the stadium, kicking conditions became increasingly difficult and Humphreys sliced two penalty attempts wide of the uprights in quick succession.

And Glasgow made their opponents pay with only minutes left to secure the only try of the match.

Having broken one tackle, Weir released Nathan who, after exchanging passes with Lemi, romped into the corner to touch down.

Weir skewed the conversion wide but made sure of the win in the dying moments with a calmly struck drop-goal.