The Leicester potter won 6-2 and will play Ding Junhui, a victor by the same margin over Shaun Murphy earlier in the day, in Sunday's best-of-17-frames final.

O'Sullivan was the man in form heading into tonight's semi-final, fresh from winning the German Masters, his first major ranking title since September 2009, and from knocking out Judd Trump in the Newport quarter-finals yesterday.

Selby, though, has done enough over the past two years to be ranked the world number one.

Although O'Sullivan started as favourite, it was easy to make the case for his opponent who delivered a safety-first performance - the clever way to play against O'Sullivan - to advance to the meeting with Ding.

After a scratchy start from both players, Selby did enough to take the opening frame.

O'Sullivan did not make a pot, but it had still been slow going and it came as some relief when a fluent 80 from the three-time former world champion made it 1-1.

Tactical

Selby was in with 34 in third frame but broke down and fell 2-1 behind. Excitement was at a premium. Selby took a messy fourth frame to draw level at 2-2 at the interval.

He moved 3-2 in front in similarly unspectacular fashion after the fifth frame went down to the last three colours.

O'Sullivan played a poor safety on the blue and it lost him the frame. Selby cut the ball into the left middle pocket before rolling in a long pink.

It came down to a tactical exchange towards the end of the sixth frame, too, and again Selby came out on top, clearing from the final red to the pink to pull two frames clear.

O'Sullivan missed a red to the green pocket at the start of frame seven. Selby then missed a blue which he had left tricky by over-screwing.

It remained messy, an attrition contest with neither man settling into a rhythm.

But that suited Selby more than it did O'Sullivan, and with a succession of visits to the table he was able to stretch his lead to three frames.

The eighth frame was all Selby, and the match was over in a hurry, to Selby's delight.

Earlier on Saturday, Ding reached his first ranking event final of the season with a 6-2 victory over Murphy.

Ding has endured a disappointing campaign, failing to reproduce the form which took him to the Crucible semi-finals last year.

But in Wales this week he has raised his performance, although he had more than a little luck when quarter-final opponent Stephen Lee looked like winning a deciding frame, only for a ringing mobile phone to distract him during a key shot on the green.

Lee missed, Ding took advantage, and against Murphy he was dominant.

Ding took a scrappy opening frame, before a break of 126 from Murphy made it 1-1.

Fluent runs of 91 and 71 from Ding gave him a two-frame cushion by the interval, making it critical for Murphy that he should go no further behind.

Duly the Englishman made a break of 90 to take the next frame, but it would be his last.

Less efficient

Ding pulled 4-2 clear with an 86, and a 75 took him to the brink of victory.

The former world champion was having just as many scoring opportunities as his opponent, but he was proving far less efficient than Ding in converting the chances into frame-winning breaks.

Both men had several openings in the eighth frame, but errors flowed. Murphy should have narrowed the gap yet after opening up a 37-point lead at 52-15 he missed a red which should have been routine.

Ding, the former UK and Masters champion, then had a chance to clinch victory in one visit but spurned it.

There was no cause for alarm though. Thanks to a poor safety from Murphy he was soon back at the table, and soon wrapping up his win.

Ding took the final red and added the black before sweeping up all the colours.