Rock steady after stunning Phelps
If you are a 22-year-old British swimmer with an unspectacular record after one Olympic appearance, and unknown outside the sport, you could not script a better way to announce yourself to the public.
Duel in the Pool has been the first event of its kind in Britain and, according to a delighted Rock, the format could spur British swimmers on to greater things.
'It'd be fantastic to beat Phelps at London 2012' - Michael Rock
When I spoke to him afterwards, the flame-haired law student told me the atmosphere at the Manchester pool had spurred him to victory.
The Manchester Aquatics Centre has been bathed in a feast of light and sound for the two-day competition, and the sell-out crowd rocked out as Rock romped home - a noise he could hear as he made his final turn in the men's 200m butterfly.
"The crowd got me through," he said. "The atmosphere was electric, they were right behind me every stroke I took in those last two lengths.
"All that was going through my head was how many kicks I need to do and my stroke count, to try to finish the race strongly on a full stroke. You have to take your mind out of it.
"Even then, you can just about hear the deafening roar of the crowd in the background through your cap, and that gets you through - but you have to keep your mind on what you need to do in the water."
Rock, who would have liked to be a pianist had his swimming not reached these heights and calls John Lennon his idol, felt no pressure as he lined up alongside Phelps, with Europe already out of the running and only pride at stake.
And the 24-year-old American master of swimming, owner of 14 Olympic gold medals, looked like he was wearing the lot as Rock won the race by more than a second.
That probably owes a lot to Phelps' decision to wear a textile swimsuit, which will be legal under 2010 rules, as opposed to Rock's 2009 swimsuit, which is 100% polyurethane and will be banned from January.
Duel in the Pool was Rock's last chance to wear the ultra-fast 2009 suit, and he took full advantage to outpace Phelps, who insisted on sporting the 2010 outfit throughout the competition.
Rock is unrepentant about the decision to harness the technology available to him - as did many other swimmers, including fellow Briton Fran Halsall, who won three events at the duel.
"I'll take any victory against Michael Phelps," said Rock. "This victory has to be taken as a mid-season thing - forgetting the suit issue, we're both in heavy training at the moment and this event is not our focus. I'm very much working towards the Commonwealth Games next year.
"I was racing in a suit which will not be legal next year but it is legal now and, as an athlete, you just try to get the best out of yourself and look for all the advantages, not just looking at the suits, every day in training when you improve on your performance.
"The great thing about next year," he added, referring to January's ban on the 2009 models, "is this won't cloud the issue. It'll just be the best athlete who will win the day, and that will be a great thing."
The immediate question which springs to mind is whether Rock would ever be able to replicate the feat if he and Phelps lined up in identical suits. When I put that to Rock's European team-mate Liam Tancock, himself a world champion in backstroke, the Devonian said Rock could win again.
"I don't see why not," said Tancock, who took third place in the men's 100m backstroke on Saturday. "There's a bit of difference in the suits and that comes down to Fina (the sport's governing body), but all we can do is race the best we can.
"Michael stood up tonight and raced hard, and came away with the victory. He touched the wall first, well done him, great job for Europe. Who knows what can happen next year. Michael's got a boost before Christmas, there's a lot of hard work to go, and he's shown Phelps is beatable."
Rock, as you may imagine, found it hard to shift a winning smile from his face as he looked back on his day's work.
"It's the first time I've beaten Michael Phelps," he said, in case that needed clarifying. "It doesn't happen every day. I've got the utmost respect for what he's achieved, he's a great athlete, a great competitor, and somehow I beat him today. I can't quite believe it. I spoke to him afterwards and he offered his congratulations.
"I just hope we have more of these events because it really gives us a mid-season lift," he added, playing down the 185-78 scoreline with which the US won the event, despite his efforts.
"We had a fantastic European team and the margin of victory is testament to America's dominance in the sport right now. They've got great athletes, let's face it. These three nations came together and achieved great personal performances, it's just America is such a great nation, they won the day."
As the temporary seats around the pool are dismantled and swimming disappears from the nation's screens, so Rock will probably find he fades from view. But he knows that is coming, and is ready to knuckle down for three more years.
"On Monday morning I'll be back doing six or seven kilometres, when it's cold at six in the morning. I need to get grounded, back down to earth, and work towards British trials in April.
"It's a funny time of year that this meet came, we're all in very hard training with the focus being the Commonwealths next year. Any performances achieved here are only a positive step, and I'm very much looking forward to the future.
"It'd be fantastic to beat Phelps at London 2012 but I need to put in a lot of hard training before then."