OMAHA, Nebraska: Michael Phelps turned the tables on Ryan Lochte in the 200m freestyle final at the US Olympic swimming trials on Wednesday, edging his rival in a thriller as both booked London Games berths.

Phelps, the former world record-holder and reigning Olympic champion, led at every turn with Lochte right on his shoulder.

Both came hard off the final turn, with Lochte putting on the pressure before Phelps's final push gave him the victory in 1min 45.70sec.

Lochte - who beat Phelps in the event at last year's World Championships in Shanghai - was second in 1:45.75.

The two are already booked for an Olympic clash in the 400m individual medley, in which Lochte beat Phelps on Monday.

Phelps also lost to Lochte in their 200m free semi-final on Tuesday - and said he had made some changes to his race tactics.