If this week in America's heartland is any indication, Michael Phelps and Ryan Lochte are going to put on quite a show in London.

The world's greatest swimmers produced their most stirring duel yet at the U.S. Olympic trials Saturday night, going stroke for stroke in the 200-meter individual medley, never more than a few inches apart.

Their arms whirled in unison on the butterfly, then again when they flipped over for the backstroke. Their heads popped out of water as though this was synchronized swimming when they switched to the breaststroke. And, finally, they both gave it everything they had coming to the wall on the freestyle.

Phelps got there first, touching nine-hundredths of a second ahead of Lochte with the fastest time in the world this year.

The scoreboard from Omaha now reads: Phelps 2, Lochte 1.

''We were probably playing the cat-and-mouse game again,'' said Phelps, who won with a time of 1 minute, 54.84 seconds. ''Then, of course, the last 50 we went crazy.''

For Phelps, it was an emphatic message on his 27th birthday that he intends to turn his last Olympics into another major medal haul. For Lochte, it was a gutsy performance coming just a half-hour after he won the grueling 200 backstroke.

''The best thing about swimming is racing and stepping up against the world's best,'' Lochte said, sounding amazingly chipper before he returned for his third race of the night, the semifinals of the 100 butterfly.

Lochte finished third in his heat and set up one last race with Phelps on Sunday.

''Tonight was probably the most pain I've endured in a swimming competition,'' Lochte conceded.