By Steve Keating

OMAHA, Nebraska (Reuters) - Michael Phelps and Ryan Lochte cruised to victory in their respective 200 meters medley semi-finals at the U.S. Olympic trials on Thursday to set up one last mouth-watering showdown between the rivals on home soil.

Phelps, who secured a trip to his fifth Olympics with a victory in the 200 butterfly on Wednesday, capped off his 31st birthday in imperious style by gliding to wall in one minute, 57.61 seconds, the third fastest time in the event this season.

But Lochte, who has been competing against Phelps in this event since 2003, followed his rival into the pool and threw down the gauntlet by clocking the year's second best time of 1:56.71.

"He's a tough competitor and I just love racing against him," said Lochte. "Every time I can get up on those blocks to race him is definitely an honor.

"Tomorrow will be a good battle between me and Michael.

"It is one of the greatest rivalries in sports from what we have both done as far as swimming."

Certainly few can match what Phelps and Lochte have accomplished in the pool.

Phelps, winner of a record 22 Olympic medals, has made the gold medal in the 200 IM his personal property taking top spot on the podium at the last three Summer Games.

Lochte, winner of 11-Olympic medals and runner-up to Phelps in the 200 IM at the 2012 London Games, is the world champion and record holder in the event and looking to qualify for his first individual event at Rio Games.

Hampered by a pulled groin he sustained in his opening event of the trials on Sunday, Lochte has qualified for the U.S. team as a member of the relay pool but the 200 IM may represent his best chance to get into an individual event.

Both men are entered in the 100 fly but Lochte described that event as a "fun race," leaving Friday's matchup as their likely final true showdown other than a possible rematch at the Rio Olympics.

"At the big meets we have great races and we are right there with each other tomorrow in the middle of the pool. It's going to be good," said Phelps. "We're going to be out and probably step on the gas a little bit more than we have in the past.

"Even if he is hurt I don't think he is going to let anything be an excuse.

"Him and I together have had a pretty decent rivalry back and forth and we've been able to really push each other and I would expect that tomorrow."

(Editing by Frank Pingue)