Ryan Murphy lost the second of his Rio backstroke titles to Russian Evgeny Rylov on Friday and the US swimmer then suggested doping had played a part in his demise.

Another morning of memorable racing saw Tatjana Schoenmaker win the women’s 200m breaststroke in a world record 2:18.95 to deliver South Africa’s first gold medal of the Games, while China won their first men’s swimming gold in Tokyo, Wang Shun coming home first in the 200m medley.

There was no easing up from Australia’s gold medal hungry swimmers, with Emma McKeon winning the women’s 100m freestyle for their sixth Olympic title in the pool.

But the celebratory mood changed after Murphy relinquished the 200m backstroke crown, as Rylov, who also won the 100, touched first in an Olympic record.

“It is a huge mental drain on me to go throughout the year, that I am swimming in a race that’s probably not clean and that is what it is,” Murphy said after finishing second to the Russian.