The second week of the 2018 U.S. Open is underway and those remaining in the main draw are duking it out for a spot in the semifinal. But the players aren't the only ones logging long hours on court: The line umpires have been making calls since the qualifying rounds of the tournament started two weeks ago.
"We're there when the ball lands that close to the line, in or out, and we have to make the call. It's a very intense concentration job," says line umpire Kevin Ware, who has been officiating full-time ever since he quit his job as a web designer five years ago. And by the end of the tournament, "everybody has put in a lot of miles of walking and made a lot of calls."
As an umpire, you never know how long or short your day is going to be, and that's one of the hardest parts of the gig, Ware tells CNBC Make It: "We will go as long as play goes. So if every match goes three sets, we could be here until 10 o'clock or 11 o'clock. We'll keep shifting with the other crew, hour by hour."