Ryan Lochte falters on 200 freestyle; Missy Franklin and Matt Grevers win gold

(CBS/AP) LONDON - Missy Franklin and Matt Grevers both won gold for the U.S. in the 100-meter backstroke on Monday, but fellow swimmer Ryan Lochte wasn't as lucky.

The Olympian has turned in two straight disappointing performances after opening the games with a dominant win in the 400 individual medley. He finished fourth and off the podium Monday night in the 200 freestyle, which France's Yannick Agnel won by a full body length against a field with gold medalists galore.

"Not so happy with that swim tonight," Lochte tweeted Monday, but promised, "Tomorrow I will be better."

On Sunday, Lochte anchored the U.S. in the 4x100 free relay, taking over with a seemingly comfortable lead. But Agnel chased him down on the final leg, giving France the gold.

Now, another defeat.

"I did my best," Lochte said. "I guess sometimes you win, sometimes you lose. I gave it 110 percent. There's probably some things I messed up on, but you live and learn. (Agnel is) a great racer. There's no doubt about it. He's quick and he showed it last night and tonight. I'm happy for him. He did good."

Frankin, coming back less than 14 minutes after swimming a semifinal heat, won the first gold medal of what figures to be a dazzling career, rallying to win the 100-meter backstroke Monday.

"Indescribable," the 17-year-old Colorado teenager said of the victory. "I still can't believe that happened. I don't even know what to think. I saw my parents' reaction on the screen and I just started bawling. I can't even think right now."

Grevers kept the gold medals coming in rat-a-tat fashion, following up Franklin's win with one of his own in the men's 100 back. For good measure, Nick Thoman made it a 1-2 finish for the red, white and blue by taking the silver.