The Lions flyer went into the game with his right thigh well strapped and was forced to come off just past the half hour mark.

The Dragons were forced into a late change at outside-half when Blues-bound Ceri Sweeney pulled out before the kick-off with a rib injury. He was replaced by 18-year-old debutant Jason Tovey.

At the other end of the scale Adam Black was making his 100th Magners League appearance.

Left-footer Tovey gave the Dragons the lead on eight minutes with a penalty goal after the Ospreys had gone offside on their 22.

But James Hook levelled the score at 3-3 three minutes later from a similar offence right in front of the posts.

Tovey had to watch as a fine drop-goal attempt rebounded off the right upright.

The Ospreys seemed to have a certain try when Lee Byrne attempted to pass out to Jonny Vaughton on the left wing, but Dragons full-back Kevin Morgan deliberately knocked on.

Hook missed the resulting penalty goal attempt and was wayward with a second two minutes later.

Soon after Williams was forced to limp off, Dragons openside flanker Richard Parks was sin-binned for tackling opposite number Marty Holah without the ball.

In first half injury-time Hook found his range with a penalty from a Dragons scrum offence which saw the home side lead 6-3 at the interval.

The best chance of a try came for the Ospreys five minutes after the break but Vaughton hit the left corner flag before going over.

And the home side thought the impressive Lee Byrne had grabbed the first try but the referee had blown up for a serious injury to Dragons centre Paul Gomer-Davies, who appeared to have been knocked out attempting a tackle on Filo Tiatia.

The game was held up for 12 minutes while Gomer-Davies was stretchered off.

A snap Justin Marshall drop-goal gave the Ospreys a 9-3 lead before Luke Charteris became the second Dragons forward to get a yellow card after a late tackle on Hook.

The first try of the game eventually arrived on 71 minutes when Brew breezed in on the right – but it was a controversial score as Hook’s pass to Byrne in the lead up looked to be two yards forward.

After the final whistle Dragons coach Paul Turner attempted to remonstrate with referee Tim Hayes about the forward pass.