Wing Rhys Shorney was sent over in the corner by outside half Jason Strange.
O'Sullivan picked up from the five metre scrum and substitute outside half Jeremy Manning converted his score.
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As an outside half and a kicker you're fully aware of your responsibilities so hopefully it'll go well.
Scotland's New Zealand-born wing Sean Maitland was also included although there was no place for outside half Greig Laidlaw.
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At outside half, Gatland will have Owen Farrell and Jonathan Sexton, while his scrum half options will be Conor Murray, Mike Phillips, and Ben Youngs.
With Munster restored to their full complement, Eoghan Hickey managed their first points from a penalty but the home side immediately struck back when, from a scrum, Humphreys put Trimble clear though referee Allain Rolland failed to notice a blatant forward pass from Ulster's outside half.
BBC: Paul Steinmetz gave Ulster the perfect start at Ravenhill
"If Jonny had come back as captain at outside-half with a new centre combination outside him, it could have been a disadvantage for England, " explained Ruddock.
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"We know that James is a talented outside-half and maybe that's his best position, " said Jenkins.
Outside-half Nicky Robinson has joined Gloucester and scrum-half Jason Spice has signed for Bristol.
Wales outside-half Stephen Jones hailed Williams as "fantastic" after he equalled Gareth Thomas's Test tries record.
Glasgow outside-half Dan Parks kicked four penalties as the visitors defeated the Dragons four penalties to two.
The outside-half added the conversion and, minutes later, a 30-metre penalty to compound the visitors' nightmare start.
He had to be replaced by wing Darren Daniel with centre Gavin Evans going to emergency outside-half.
"As long as I am playing, I am happy, whether it's centre, outside-half or full-back, " Hook said.
Outside-half Nicky Robinson edged them further ahead with a penalty before Wales' record try scorer Gareth Thomas took centre stage.
Outside-half Carter, 26, plays his rugby with Super 14 side Crusaders but is said to want to play in Europe.
"We are obviously aware of Dan's qualities as an outside-half from numerous encounters with Glasgow over the years, " Young said.
Flanker Waldrom then charged through and over to finish off Flood's break with the outside-half kicking his fifth conversion of the game.
Evans' views were supported by former Wales captain and outside-half Jonathan Davies.
The 28-year-old outside-half has recently had his place in the side questioned, but the World Cup winner says criticism no longer affects him.
The Scarlets brought on Wales outside-half Stephen Jones after half-time and he had an immediate impact, sending over an early penalty to reduce the deficit.
Four penalties from outside-half Ronan O'Gara and a late try from Denis Leamy sent Munster into the quarter-finals for the 10th season in a row.
It was the Ospreys who got the first points of the evening with outside-half Shaun Connor sending over a penalty after only a couple of minutes.
It was the Scarlets who got the first points of the afternoon, with young outside-half Rhys Priestland sending over a penalty after Bristol had been caught offside.
"We want to play the game in a certain way, " revealed Jones, who on Saturday is set to join another Wales outside-half, Neil Jenkins, on 87 caps.
First the outside-half planted a penalty goal and followed that up by converting his own try after latching onto the end of full-back Anthony Floch's kick ahead.
But Ronan O'Gara's penalty pushed them two scores clear and the outside-half's kick proved crucial after Delon Armitage crossed over for a try with two minutes remaining.
The result was left in no doubt when the outside-half put Gear into space and the winger ghosted through an absent defence for his third try in as many Tests.
The Ospreys started brightly, taking only a minute to gain their first opportunity to earn points, but the normally reliant boot of outside-half James Hook misfired as he sent his penalty wide.
And Devereux hopes that Hook, who has indicated he wants to play outside-half for Perpignan, is not the first of a clutch of Wales stars who may be attracted to play in France.
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