Ron Violette's eyes shift like he's being hypnotized by a swinging pocket-watch.
Occasionally, he leans against a wall, but he never takes his focus off the small green blur within his sight.
Violette, is among the 3,000 tennis officials nationwide who qualify to judge at the U.S. Open, considered one of the four major tennis tournaments known internationally.
Of those 3,000, only 300 are selected each August to serve as chair umpires and line judges during matches between the world's most elite players.
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Violette, a regular at the event, has been invited 12 times.
He never swung a racquet himself until graduate school at UNC Chapel Hill, where a friend took him to the courts and showed him the basics.
Growing up in Concord, baseball and basketball were Violette's favorite sports, and he played them throughout his school years.
After graduating high school in 1966, he made the switch from player to referee, officiating those games, first at the high school level, then college, including the first televised women's basketball game in the 1970s.
He added tennis umpiring to his resume in 1978, while on staff at the University of Memphis. "I saw an ad in the paper," he said. "They were looking for tennis officials." So he decided to give that a try.
It was much simpler back then, said Violette, 62, who went to the clinic and impressed the instructors.
There are different levels of certification through the Unites States Tennis Association. To be at the professional level, like Violette, officials must attend clinics, pass written tests and evaluations, and log plenty of experience refereeing.
During the U.S. Open, seven line judges, of which Violette is one, take the court and share the responsibility for calling whether the ball has fallen inside or outside the line. The chair umpire, who sits perched above the net, has final authority on calls.
Hearing the powerful whack between racquet and ball up close can be a thrill, said Violette, who has judged matches where tennis greats like Pete Sampras, Jimmy Connors and Ivan Lendl have traded volleys, punishing the ball back and forth across the court.
Sometimes it can be stressful, especially if the player is known for having a temper, like John McEnroe, who has offered a few curt comments to Violette in the past.
During one match, the hot-headed pro's frequent low grumblings after calls erupted into a direct comment to Violette. "He mumbled something like, 'You finally got one right.'"
The seasoned linesman never spoke back to McEnroe. "We are not supposed to interact," he said. "You have to sit there and take it."
Violette's career as director of student services for Cabarrus County Schools probably helped him prepare for such instances.
One job responsibility was to make decisions regarding student expulsion and long-term suspension cases.
Retired in 2003 after 20 years with the district, he now spends his time officiating two to three matches each week.
Occasionally, he picks up a racquet himself, but it's different, he said. "Generally, it's a friendly match. It's all in fun."