Caitlin McClatchey eased into the semi-finals of the women's 200m freestyle, winning her heat in impressive fashion on Monday morning.
The Scot, Commonwealth champion over the distance back in 2006, produced a strong finish to her heat to win it in a time of one minute 58.03 seconds.
In doing so, she beat the Camille Muffat, the Frenchwoman won claimed the 400m title on Sunday night when she dethroned Briton Rebecca Adlington.
McClatchey qualified as the joint seventh fastest swimmer overall for Monday evening's semis.
However, her team-mate Rebecca Turner's effort of 1:58.98 was not good enough for her to progress - she missed out by just 0.02secs.
McClatchey, sixth in this event in Beijing and now competing in her third Games, had already taken to the pool in a relay earlier in the week and said that had helped.
She said: "I had great confidence from the 4x100 because I was on form so I was hoping I could do a good job this morning and to win my heat against some of the best girls in the world was fantastic.
"Obviously they probably were a bit tired from the 400 last night, but who cares?''
Allison Schmitt, second to Muffat on Sunday, also won her heat but the fastest qualifier was Italy's world-record holder Federica Pellegrini, who swam 1:57.16.
Another British swimmer missed out on qualification by just 0.02secs in the following event, the men's 200m butterfly.
Joe Roebuck's time of 1:56.99 was only just outside the top 16 who progressed to the semi-finals. Team-mate Roberto Pavoni (1:57.55) also bowed out.
Defending champion Michael Phelps was only third in his heat, his time of 1:55.53 seeing him finish fifth overall, as Austria's Dinko Jukic set the fastest qualifying time of 1:54.79.
There was better news for Britain in the women's 200m individual medley, with Hannah Miley moving into the semis.
She finished fourth in a loaded final heat, her time of 2:12.27 being good enough for 10th place overall.
Miley, who was fifth in the 400m IM on Saturday, said: "I'm really, really happy, it's great to make it back into the semi-final.
"I always take it one stage at a time and now I'm in the semi-final and the next stage is to make the final. You can't predict how the other girls are going to swim, it's never how everyone predicts but I feel a lot more relaxed after the 400m.''
However, the other GB competitor, Sophie Allen, (2:14.72) did not progress and afterwards admitted she was "gutted" at missing out.
China's Ye Shiwen remains very much on course for a gold-medal double and looks the one to beat.
The 400m champion's time of 2:08.90 was more than a second and a half faster than any of her rivals.