World Championship silver medallist Ellen Gandy's failure to qualify for the 200m butterfly final continued Team GB's struggles in swimming competition at the Aquatics Centre on Tuesday.
The 20 year old, the seventh fastest women in the event's history, finished fifth in her heat in 2:09.92, a full four seconds short of her personal best time; potentially her final contribution in her home Olympic Games.
Jemma Lowe did qualifiy for the semi-final after finishing second in her heat to continue Britain's involvement in the event, but Gandy's failure to finish in the top 16 is another blow to a target of six swimming medals this summer, a total that currently lies at one with six days of competition remaining.
Rebecca Adlington won bronze in the 400m freestyle on Sunday and is favourite to defending her 800m title from Beijing on 3 August. Kerri Ann Payne, the first Team GB athlete to qualify for London 2012, goes into the women's open water race on 9 August as a genuine contender for gold.
Michael Jamieson did deliver some positive news for Team GB with the first swimming British record of London 2012 in qualifying for the 200m breaststroke semi-final.
The 23 year old finished second in the third heat in 2:08.98, qualifying second fastest for the semi-final behind Athens 2004 silver medallist Dániel Gyurta.
Former World Championship finalist Andrew Willis also reached the semi-final after winning heat five.
Jamieson said: "It's easy to swim when you have some confidence. It's so amazing to be here and I'm really happy with that. I think I have another gear so I am looking forward to tonight."
Elsewhere, Britain's male 4x200m team qualified for the final after finishing third in their heat behind the team from United States and Australia.
The quartet of David Carry, Ross Davenport, Rob Bale and Robbie Renwick will go into this evening's final with an outside chance of a medal, with the American team set to introduce both Ryan Lochte and Michael Phelps into their team.