Josef Craig was dumbfounded after breaking the world record in the S7 400 metres freestyle as he stood at the summit of a number of top performances by British swimmers this morning.
While the 15-year-old stood out, there were four second places and two thirds heading into tonight's finals which bodes well for British hopes of adding to their 31 medals.
Craig cut his own best by nine seconds as he hurled down a marker in four minutes 45.79 seconds.
The South Shields-born teenager's time saw him dip 1.37secs inside team-mate Jonathan Fox's world record set at last year's European Championships in Berlin.
Craig was completely taken aback and said: "I thought 'God I've just done a massive PB, that will be my achievements done for this competition'.
"But then I got my focus back and saw it was a world record next to the time and I just thought 'there's a problem with the clock here - I can't break a world record yet, I'm still young, just take it one step at a time'.
"I just don't know what to say about that, it's just amazing."
Craig trained in Manchester for three weeks ahead of the holding camp immediately before the squad travelled to London, something from which he has no doubt benefited.
He added: "I've been training really hard but I never thought there would be a world record time in there. It just goes to show what amazing help I've got up at Manchester.
"I couldn't have done it without them and the support I've had - the pace work from Jon Fox, he's been a very big help, and Mick Massey and Andy Scanlon, the two coaches.
"They have just really helped us and without them I couldn't have done this."
Fox was second fastest through in 4mins 49.91secs making the possibility of two Britons on the podium tonight a very real prospect.
The 21-year-old was magnanimous about his younger team-mate wresting his world record and said: "Josef is 15 and has been training really well and hats off to him for breaking it.
"I am a good team player, I take a defeat when I get one and we'll see - I'll come back fighting tonight and hopefully there will be two Britons on the podium so we'll see what happens."
Susie Rodgers and Heather Frederiksen qualified second for their respective races although they both face almighty battles to get to the top of the podium.
Rodgers was second into the women's S7 400m freestyle in a new European record time of 5:22.08.
The 29-year-old double medallist is though realistic about the chances of beating six-time London gold medallist Jacqueline Freney who set a new Paralympic record of 5:01.04, more than 21secs ahead.
Rodgers said: "She is so far ahead, I am not going to be dropping 21 seconds.
"She did a really good swim so good for her."
Rodgers has also twice been edged out of the medals into fourth but she added: "As long as I PB I'm happy. I got the bronze without PBing but we are here to get quicker and it makes the training worthwhile.
"If you get fourth, you get fourth but I will go out and try my best.
"To be honest, they are all so close. There are about three or four of us who are pretty much on a level playing field there so it is anybody's, the silver and the bronze."
Similarly Frederiksen will face quadruple 2012 gold medallist Jessica Long.
Frederiksen successfully defended her S8 100m backstroke title on Tuesday and today she again displayed her racing instincts when she refused to give an inch to Australian 13-year-old Maddison Elliott in the lane to her left.
The Briton clocked 1:07.53, 1.47secs behind Long who set a new world record, and she appears on course to add another medal to the silver she won in this event in Beijing four years ago.
Frederiksen said: "That is the life of an athlete.
"Me and my coach have a good racing plan and this morning went to plan.
"The first 50 was nice and easy and comfortable so [it's] promising for tonight."
British women filled the slots from second to fourth in the SM9 200m individual medley.
Just 1.28secs separate Steph Millward, Louise Watkin and Claire Cashmore.
Watkin returned from her silver in the S9 50m freestyle to clock 2:38.47, 0.74secs behind Millward.
She admitted she was still cock-a-hoop after last night's exertions, saying: "It took me a while to get to sleep last night and I haven't had much rest.
"So I just went into the heat this morning to see what I could do."
Cashmore was fresh-faced after her 2:39.21 and insisted there could be a British clean sweep despite the presence of Natalie du Toit, winner in 2004 and 2008.
She said: "Hopefully it will be another exciting race tonight with all three of us going.
"She is not unbeatable and i definitely think we can and hopefully it will be a one-two-three from Britain - the order I'm not saying but hopefully in my favour."
James Crisp was third into the SM9 200m individual medley while Andrew Mullen (S5 50m backstroke), Aaron Moores and Daniel Pepper (SB14 100m breaststroke) and Sean Fraser and Thomas Young (S8 100m freestyle) all made it through.