David Foot column: The first time I went to Keynsham to see that embryonic snooker talent, Judd Trump, his name then already mentioned by the experts in tones of real excitement, he seemed to me not much taller than the table.

He was a shy, polite schoolboy of few words, rather embarrassed by the increasing amount of praise and acclaim he was beginning to acquire.

This week I returned to congratulate him on beating his one-time idol, Ronnie O'Sullivan to reach the semi-final of the Glasgow grand prix tournament – and to discover how much he had changed

He's £20,000 richer, of course. His was the name, and relatively new face, the pundits and thousands of TV watchers found themselves talking about. He is still only 19 and is seen by many as a future champion. "I'm getting more and more relaxed and comfortable in the bigger tournaments and really think I can go all the way", he tells you, ambition momentarily lighting up his face.

At Glasgow, his form didn't please him. He says he revealed only about 40 per cent of his potential. Nothing too much wrong with the temperament, though – it's one of his envied strengths. And in the words of his mentor, Derek Curnow at the Keynsham snooker centre, "absolutely nothing fazes him".

Nor was O'Sullivan, one of the game's mavericks, anything like his best last week. He has always been a player of moods, the brilliant as well as the darker ones. It is hard to know what he thought about Trump's precocious skills in mocking the pair's disparity in experience.

There were few outward signs of generous spirit and congratulations from O'Sullivan for his innocent young adversary. Yet snooker is not particularly renowned – with some notable exceptions – for its plentiful compliments. Press the young West Countryman on the subject and he says: "Not much talking or exchanges go on among the players. Ronnie said nothing to me after our match. I didn't expect him to."

Snooker has a theatrical setting, its table dramatically lit for the game in progress. It can be a solemn business. Many of the players' faces are wan and tension-filled, as the cameras zoom in

Judd has discernibly matured, still in that pleasing, undemonstrative way. These days he has a distinctive modern haircut and a fixed expression that doesn't parade too many emotions. There is something slightly vulnerable about him. Housewives, who like viewing the snooker on the telly, have a motherly regard for him. Not many of them have any idea of the hours he practices or the necessary self-discipline.

He is often on the road or maybe at times in a plane. His dad, Steve, a lorry driver, takes him thousands of miles to fulfil the busy itinerary. Mum gets too nervous, preferring to watch on the television. Brother Jack has given up any snooker aspirations he had, switching to golf.

Judd was assured of his place in snooker history when early in 2004 he became the youngest player to make a maximum match-play 147 break. He was 14 years and 208 days old. Since then, the century-breaks have piled up. Now it is for him to gain added confidence and refinement of his shots, in the incessant practice routine – six hours a day and at least five days a week – as he aims for the top.

Last week's progress was the highest point yet in his ascending profile. He produced some gasps of admiration as he skilfully hauled himself back into contention after trailing 4-1 against John Higgins, twice world champion. He was conscious of his mistakes but didn't allow them to affect his game.

It has been suggested to him by snooker's authorities that he might benefit from a media course. The idea was rejected. He is growing in self-confidence in his own way. His natural, quiet style is part of his appeal. "I love the game and get so much enjoyment out of it. But I'm certainly not addicted to it. I don't go near a table at the weekend unless there's a tournament to think about."

You suspect he is now enjoying the big-tournaments, with its glamour and TV interviews. That pensive expression, as he attempts to find the perfect balance between break-building and safety, while earning applause for his trademark long, daring pots, could make him snooker's face of the future. Those long, lonely hours of practice at Keynsham haven't been wasted. He's now ranked 28 – and climbing.