He moved into the quarter-finals of the World Championship yesterday but only after lurching from awful to awesome in a manner that would have had an assessor into match-rigging desperate for a stiff drink or three. O'Sullivan is many things, but easy to read he is not.
Yesterday he completed a 13-8 win over Darren Morgan yet that scoreline conceals a match that made a switchback seem like an even glide. From 4-1, O'Sullivan lost seven frames in succession only to rattle off the next nine, five of which comprised yesterday's session. What will happen when he meets the four-times champion, Stephen Hendry, in the next round is anybody's guess.
"I don't know how I can play so badly and still be in the tournament," he said, "I played better when I was 12." Which summed up some of misses that would have had him cracking his cue over his knee had he performed them before he was old enough to wear long trousers but harshly neglected some pots that bent the bounds of belief.
Poor concentration is O'Sullivan's Achilles' heel and yesterday he adopted the "spend a penny" remedy, going to the toilet between frames to focus his brain. The result was a sharp rise in The Crucible's water rates and a similar increase in his form as breaks of 64, 73, 53 and 48 testify.
Hendry, of course, gives the impression he could concentrate in a crche of three-year-olds and yesterday he took his unbeaten run at The Crucible to 17 matches with the demeanour of a man swatting an irksome fly. Ahead 11-5 overnight against Malta's Tony Drago, he shot over the line in 40 minutes, pausing only to drop a frame on the way.
To the unpractised eye Hendry's snooker looked fine but when a player spends his professional life a kiss away from perfection, faults loom large. "I missed a pink to win the match 13-5," he said glumly. "It's something that's been missing this season, the ability to kill matches with one visit to the table."
His main preoccupation, however, was another ideal, a 147 break. "I've never achieved a maximum on television," he said, "it's one of the few ambitions I've not achieved." With a special prize of £147,000 on offer at this tournament, the moment could not be better.
Results, Sporting Digest, page 47