Ronnie O'Sullivan seized the initiative in the opening session of his Embassy World Championship semi-final with Stephen Hendry as he galloped into a 6-2 lead in the best-of-33-frame encounter.

O'Sullivan will leapfrog deposed title holder Mark Williams into top slot in the 2004-2005 snooker rankings by merely reaching the final on Sunday where he would face either Graeme Dott or Matthew Stevens.

But the main priority for the 28-year-old from Chigwell will be to capture his second world crown and bury the Crucible Theatre hoodoo that Hendry holds over him - and he is well on the way to achieving that objective.

The 'Rocket' scored heavily whenever he was in among the balls particularly after the interval and Hendry did not help his cause with several uncharacteristic errors.

There has been no love lost between the pair since O'Sullivan questioned seven-times champion Hendry's sportsmanship before their meeting in the 2002 finals - but a huge amount of mutual respect for each other's ability.

The Scot has won all three meetings with O'Sullivan at Sheffield and also triumphed this season in the final of the British Open and the semi-finals of the UK Championships.

But O'Sullivan, under fire for some of his behaviour around the table in the past fortnight, went into the match as overwhelming favourite at 7-4 on with bookmakers Ladbrokes to reach his second world final.

O'Sullivan started in confident fashion after Hendry had failed to cut a pink into the black pocket and a break of 85 to the final yellow won him the opening frame in only 10 minutes.

O'Sullivan was first among the balls in the next but left a red hanging over a pocket and a run of 61 by his 35-year-old opponent proved decisive.

Hendry missed a long red into the green pocket in the third frame to let O'Sullivan in for a useful 33 and he gleaned another break of 47 to restore his advantage.

The final frame before the interval was an uncharacteristic affair strewn with errors from both players and it lasted nearly half an hour.

O'Sullivan led 54-5 and then Hendry broke down on a break of 32 after missing a straightforward looking blue and conceded after his opponent snicked in the final brown.

O'Sullivan went into over-drive when the players returned to the arena and a 127 clearance to the pink gave him his 11th century of the championships and the 49th in total of the tournament.

It was a similar story in the next as O'Sullivan raced to a break of 67 before a vicious kick saw him miss the frame-clinching black but Hendry conceded after his opponent potted one more red.

Hendry paid dearly in the next for breaking down on 39 when he failed to cut a red into the black pocket and in stepped O'Sullivan with a 98 clearance.

It was vital for Hendry to stop the rot in the final frame and he was on for a 147 maximum after potting 11 reds and 10 blacks. But then he snookered himself on the black and had to be content with trimming O'Sullivan's lead to four frames.