AP Photo/Vadim Ghirda

American Steve Johnson trailed reigning gold medalist Andy Murray 3-0 after 10 minutes of their Olympic quarterfinal Friday - and it would have been even less time had Johnson not spent a couple of minutes arguing with the chair umpire over an ace by Murray that was called in. Johnson had lost as many challenges as he'd won points at that juncture: 2.

The Hawk-Eye system used when a player challenges gets the final word on whether a ball is in or out. It cancels out most complaints about calls - but not all of them.

"We’re both agreeing on a mark and there’s only one mark there and it’s clearly half an inch wide, and if it says it's good I have a hard time having faith in a system that I think is broken," Johnson said later.

He went on to lose the first set 6-0, winning just eight points, but by late in the third set, the 22nd-ranked Johnson would be six points from winning the match. Murray, though, has been in this situation many times before - he's won three Grand Slam titles while Johnson is coming off his first appearance in the fourth round at a major - and the second-seeded Brit rallied for the 6-0, 4-6, 7-6 (2) victory in 2 hours, 11 minutes.

Johnson's day got much better when he and U.S. teammate Jack Sock later won the bronze medal in men's doubles.