Michael Phelps' comeback to competitive swimming has continued in impressive fashion.
The most decorated Olympian of all time has beaten rival Ryan Lochte in the 100 metres butterfly and notched up the second fastest time of the year in Athens, Georgia.
Phelps posted a 51.67, his first swim under 52 seconds this year, in just his fourth meet after a 20-month retirement.
He easily beat his times in the event from his previous three meets but still has work to do to match his 51.21 winning time from the 2012 London Games.
Only Russian Vyacheslarus Prudnikov, with 51.60 has been faster this year.
Lochte was second in 53.08 with Matthew Josa third in 53.64.