By Alan Baldwin

RIO DE JANEIRO (Reuters) - U.S. coach Billy Walsh questioned the judging after his lightweight Mikaela Mayer lost her quarter-final on points to Russian Anastasia Beliakova at the Rio Games on Monday.

"To be honest, I've just had a look at the judging. It was crazy," Walsh told reporters. "Are they looking at the same bloody fight or what?

"Her performance was excellent, she gave everything she had ... I thought she did enough to win it."

The judges' tallies showed that one had scored the fight as a 38-38 draw while the other two came down 39-37 on the side of the Russian, who won 2-0 and is now assured of a bronze medal for reaching the last four.

All three judges awarded at least one round to Mayer, however.

Mayer, one of two U.S. women in the Rio boxing tournament with the other being reigning middleweight champion Claressa Shields, felt she could have swung it with a few more combinations.

"It was a close fight so it makes it even more disappointing," she said.

"I thought I might have pulled it off at the end but ... I also know this is boxing. If you let a fight get that close, you don't know who they are going to give it to."

(Reporting by Alan Baldwin; Editing by Mark Lamport-Stokes)