Great Britain's Sascha Kindred is on course for a 13th medal after qualifying for the final of the men's S6 50m butterfly.
The Paralympian, who won silver in the men's SM6 200m medley, had a good start out of the blocks but failed to make up time on China's Xu Qing, who blasted into the lead.
Qing managed to finish the heat in a time of 31.37s, while Kindred managed to touch the end of the pool in a time of 33.19s.
Kindred will line up in lane six in the Aquatics Centre for the final this evening.