Ellie Simmonds shook off the cobwebs as she returned to her domain to qualify fourth fastest for Tuesday night's S6 50 metres freestyle final.
The 17-year-old has already cemented her place as one of the faces of London 2012 and her appearance behind the blocks prompted wild cheers at the Aquatics Centre.
Two titles and two world records in the SM6 200m individual medley and S6 400m freestyle have already come her way although it could well prove troublesome for Simmonds to add the one-length dash to her roll call.
Fifth in Beijing, she clocked 36.45 seconds behind Holland's defending champion Mirjam de Koning-Peper, American Victoria Arlen - second in the 400m - and Tanja Groepper of Germany.
The Walsall-born swimmer said: "It's going to be a tough race. The 50m free is my fourth best event but it helps develop my 100 free for later on in the week. I am really achy this morning from my 200IM: it was a bit of a killer. To do that time nearly on my PB and the way I am feeling I am really happy so hopefully I can go out there and do a PB. It's going to be really tough to medal."
Great Britain's Heather Frederiksen was the fastest into Tuesday night's S8 100m backstroke final in which she is the defending champion.
The 26-year-old produced an emphatic performance to reach the final the fastest by some distance with more than four seconds separating her from American Jessica Long in 1min 17.63secs.
Stephanie Millward was second into the S9 400m freestyle as she looks to claim her third medal of the Games. The 30-year-old did not compete in this event in Beijing, where fourth in the 100m backstroke was the closest she came to the podium, but so far in London Millward has a silver and a bronze to her name.
Newham-born Amy Marren, who was inspired to take up swimming by Simmonds' double gold in Beijing, was fourth and Lauren Steadman seventh.
Oliver Hynd was third into the S8 100m backstroke with ParalympicsGB team-mates Thomas Young and Sean Fraser occupying the two places directly behind him. The 17-year-old claimed silver ahead of his brother Sam in the S8 400m freestyle last Friday and on Tuesday he finished in 1:08.59 as he looks to add a Paralympic medal to his 2011 European bronze.