Dutch flyer Ranomi Kromowidjojo is on course for the sprint double after posting the fastest qualifying time in the opening heats of the women's 50m freestyle on Friday.
The Netherlands' newest swimming star backed up from her triumph in the 100m freestyle Thursday with the quickest time of 24.51sec in a Dutch one-two with Marleen Veldhuis into the night semis.
Kromowidjojo, 21, of Surinam-Indonesian heritage, holds the year's fastest times in both the 50/100m freestyle and is looking to convert her supremacy on the clock into Olympic gold medals.
She is in demand after her brilliant 100m victory in Olympic record time and got little sleep last night heading into the morning heats of the 50m.
"I went to bed at 12 (midnight) and got up at 7 (a.m.). I was just thinking about gold, gold, gold. It's madness on my Twitter account," Kromowidjojo said.
"Everybody in the Netherlands is so supportive."
Kromowidjojo is on track to become the new sprint queen as Olympic champion Britta Steffen (24.70) and world champion Therese Alshammar (24.77) were fourth and sixth fastest respectively.
Steffen is under pressure as Germany continue to struggle in the pool at the Games, where they have not won a swimming medal and face the ignominy of not making a podium appearance for the first time at an Olympics in 80 years.
"I knew that I had to give it my all, it doesn't help to use tactics," said Steffen, who beat American Dara Torres for the 100m freestyle gold in Beijing four years ago.
On Germany's failure to yet claim a swimming medal, she added: "It is difficult. I see a lot of negative press and I feel unfairly treated. I gave everything I had."
Sweden's world champion Alshammar, in her fifth Olympics, has been battling a pinched nerve in her neck which forced her out of the 100m event in London.
"I am pleased that I was able to start despite my disc injury," Alshammar said.
"For a sport like this, you want to make sure you have full movement, being healthy is the most important thing and you really need unrestricted movement.
"When you train a lot you want to be able to participate, so I'm happy I'm through."