But the unpredictable O’Sullivan, who is becoming as renowned for his mood swings as his on-table exploits, may not even know himself which side of his personality will come to the fore.

The first Ronnie is the snooker genius. Fast, instinctive and deadly accurate, he is regarded as being the most naturally talented player of all-time.

Last season, he exhibited these qualities to win the Irish title, one of six he captured during the 2000/01 campaign.

O’Sullivan defeated Stephen Hendry 9-8 in the Dublin final and landed the Embassy World Championship title for the first time a few weeks later.

Life seemed sweet in the months that followed his Crucible triumph but the second Ronnie was never far away.

This side of his character is darker and more complex and could prove to be the barrier to O’Sullivan dominating the game in the same way Steve Davis and Stephen Hendry did during the last two decades.

It is manifested in a devil-may-care approach to the sport and a nonchalant, almost petulant, attitude to defeat.

The 26-year-old last demonstrated this split personality during last month’s China Open in Shanghai.

After winning his first round match, O’Sullivan entertained the media in his post-match press conference by singing the theme song from the TV show Happy Days to demonstrate his contentment.

But a few days later he clearly lost heart when he went 3-1 behind against Mark Selby in the quarter-finals and claimed he was not bothered when he eventually lost 5-3.

‘‘I don’t care that I lost - it just doesn’t bother me,’’ he said. ‘‘I’m quite pleased in a way because I’ve just had a stomach full of snooker.’’

In the past, O’Sullivan has attempted to rid himself of the second Ronnie by seeking treatment for depression at the Priory Clinic and joining a support network organised by the Samaritans.

But it remains clear that he is still troubled and at the Thailand Masters a fortnight ago his love-hate relationship with snooker was more hate than love.

‘‘I’ve achieved what I want to in snooker and can rest peacefully now,’’ O’Sullivan said. If I never picked up another cue it wouldn’t bother me.

‘‘The game helps pay my mortgage and maintains my lifestyle but it’s not my top priority.’’

"Whichever of the two Ronnies shows up in Dublin, he will have to be in top form to stop Stevens, who produced an impressive performance to edge perennial crowd favourite Jimmy White 6-5 in the first round on Wednesday.

The Welshman compiled seven half century breaks to reach the quarter-finals for the third year in succession.

If Stevens plays like that again, O’Sullivan could find it is a case of goodnight from him.

Meanwhile, Peter Ebdon and Ken Doherty set up a semi-final showdown by winning through their respective quarter-finals yesterday.

Ebdon beat world number one Mark Williams 6-4 to subject the Welshman, celebrating his 27th birthday, to a fifth defeat in six matches during a miserable Irish Masters campaign since his debut in 1998.

Dubliner Doherty delighted his home town supporters by defeating LG Cup champion Stephen Lee 6-4 to record the first victory for an Irishman in the event since 1998, when he appeared in his second Irish Masters final.