The Welsh left-hander, devastated by the death of his mother in November, only recovered his appetite for the game last month when his defence of the Irish Masters ended in a 9-8 defeat by Stephen Hendry on the final black of the tournament. His triumph yesterday caused a long build-up of emotions to erupt.
Perhaps after such a bereavement, snooker never seems quite so important again. Certainly, in some strange way, it released the last few inhibitions of Dennis Taylor in 1984 when he won his first major title, the Rothmans Grand Prix, in inspired fashion after his own mother had died only a month earlier.
Morgan acknowledged last week that he had become "harder" after the immediate shock had passed. Aided by some inspiring words from his manager, Ian Doyle, Morgan demonstrated not only his familiar resolution in the face of adversity but also the nerve to clinch a big victory on snooker's most famous stage.
The 21-year-old O'Sullivan, whose season has encompassed two titles, two other finals, one abject surrender and two first-round losses to opponents not really in his class, led 9-7 overnight but did not score in yesterday's first two frames as Morgan recorded his third century of the match, 116, and a break of 59.
O'Sullivan, whose first-round 147 maximum earned him pounds 165,000 to add to pounds 16,800 prize money, led 10-9 but as he admitted after the defeat: "I wasn't scoring heavily enough in the balls."
Making breaks of 61 and 40 helped Morgan regain the lead at 11-10 and, by dramatically doubling the tie-break black, he went two up with three to play. O'Sullivan levelled but Morgan's 84 after a difficult red was the only score in the decider. "Luckily, there was no safety so I had to go for it," he said.
Hendry became Morgan's quarter-final opponent after an unexpectedly routine 13-8 win over Mark Williams. The 22-year-old Welshman led 4-1, 6-4 and 8-6 on Friday, but couldn't get started yesterday as the world No 1 extended his Crucible winning streak to 27 matches.
Lee Walker, the world No 189, whose 13-10 victory over Alan McManus, twice a semi-finalist, guaranteed him pounds 31,500, a startling increment on the pounds 275 he earned in the whole of last season, acknowledged Morgan's role in his recent improvement. "After two years on the circuit I was going nowhere. Darren said he would practise with me and we played every day. "
Alain Robidoux, the Cana-dian No 1, became Walker's quarter-final opponent when he cruised through the evening session to beat Stefan Mazrocis, the world No 81 from Leicester, 13- 9.
Anthony Hamilton, whose 10-9 defeat of Jimmy White assured him of a place in the elite top 16 next season for the first time, began like a potting machine in establishing a 4-0 lead over the 1991 world champion, John Parrott, with breaks of 46, 43, 50, 63, 94 and 117. Parrott, who had scored only nine points thus far, responded in similar vein with runs of 66, 66, 88 and 86 to start their middle session tonight level at 4-4.Reuse content