Ryan Lochte registered his second consecutive victory over rival Michael Phelps at the United States National Championships with a gritty win in the 200 metres backstroke on Saturday.
Lochte's time of one minute, 55.58 seconds, the second fastest in the world this year, gave him the edge over world record holder Aaron Peirsol and Tyler Clary, with Phelps finishing fourth in 1:56:98.
The 2008 Olympic champion led from start to finish but had to hold on in the final 50 metres as Peirsol, Clary and Phelps all carved into his lead after he posted the fastest splits in each of the first three lengths of the pool.
"I don't want to do that event ever again," Phelps told reporters.
"Although I did what I wanted to do... swim under 1:57.
"I tried to be more conservative the first 100 so that I wouldn't completely feel like I was standing still the last 20 metres, which is usually how I feel at the end of a 200 back."
Lochte also beat Phelps in the 200 meters individual medley on Friday.
In the women's 100 metres freestyle Dana Vollmer swam the second fastest time in the world this year to edge Jessica Hardy, touching in 53.94 seconds.
In other events, Rebecca Soni easily won the women's 200 metres breaststroke in a time of 2:21.60, more than five seconds ahead of Amanda Beard in second place, and Eric Shanteau touched in 2:10.09 to win the men's 200 metres breaststroke.
Chad LaTourette posted the fastest time in the world this year in the 1,500 metres freestyle to win in a time of 14:55.39 and Chloe Sutton won the women's 800 metres freestyle in a time of 8:24.77.