Hannah Miley, David Carry and the women's swimming sprint freestyle relay will provide home representation in Saturday's finals after the first morning of Olympic competition which saw the Queen make an appearance at the Aquatics Centre.
Miley will contest the 400 metres individual medley, in which she won the silver medal at last year's World Championships, in what is going to be an almighty battle to reach the podium.
Her fellow Scot Carry reached the 400m freestyle final, "a dream come true" for the swimmer who, at 30, is the oldest member of the Great Britain team.
The sprint freestyle quartet of Amy Smith, Jessica Lloyd, Caitlin McClatchey and Rebecca Turner squeezed into the final in equal seventh and in the final they will have the former world silver medallist Fran Halsall in their midst.
In Carry's event, defending champion Park Tae Hwan was disqualified for an apparent false start while world record holder Paul Biedermann failed to make it through.
Miley is strongly fancied to secure Britain's first medal in the pool. The Garioch swimmer's time of four minutes :32.67 seconds at the Olympic trials had been the fastest in the world until last month when world champion Elizabeth Beisel lowered her own textile world record at the American trials.
She made it through to the final in sixth while Aimee Willmott was 11th on her Olympic debut, 28 years after her father Stuart competed at the Los Angeles Games.
Miley pulled out a superb freestyle leg which saw her touch in 4:34.98, which bodes well for the final, with defending champion Stephanie Rice of Australia in second.
Beisel lowered her own textile world record to 4mins 31.66secs and the question is how much faster she can go, training alongside the likes of Ryan Lochte in Florida clearly paying off.
Miley said: "I'm really looking forward to it. Hopefully, I'll get clear of this lactic acid that's sitting in my system and enjoy tonight."