United States duo Ryan Lochte and Tyler Clary will do battle in the men's 200m backstroke final after winning their semi-final heats.
Lochte cruised through the race, leading for much of the duration, but had to raise his game to ward off a strong finish from Ryosuke Irie of Japan.
Clary was made to work for his victory, facing stiff competition from Irie's compatriot Kazuki Watanabe and Zhang Fenlin of China.
The American battle hard, hitting the side almost a clear second ahead of Zhang and making the last eight as the fastest qualifier on 1:54.71.
The men's 200m backstroke takes place at the Aquatics Centre tomorrow evening.
