Arlington’s Denis Kudla returns the ball during his match against Australian qualifier Samuel Groth during the Citi Open. Kudla lost in straight sets. (Toni L. Sandys/THE WASHINGTON POST)

If this were Wimbledon, ESPN’s cameras would have cut to Vladimir and Lucy Kudla each time their son Denis lunged in vain at a serve that blasted past him like a lightning bolt from Zeus.

But it was Washington’s Citi Open, instead, with no player guest boxes on the 2,500-seat grandstand court of the William H.G. FitzGerald Tennis Center. So Kudla’s parents looked on Monday from an unobtrusive corner of the bleachers, with Lucy sitting about six rows up and Vladmir perched on the row just above her.

“Denis has told us that players are as sensitive as animals,” Vladmir explained before the first-round match. “They can see, out of the side of their head, how their team, their family and their friends are acting.”

That’s why whatever concern his parents felt was imperceptible as Kudla was pummeled by 20 aces en route to a 7-6 (7-2), 6-2 defeat at the hands of Samuel Groth, a 6-foot-4 Australian qualifier credited with the fastest serve ever clocked, at 163 mph.

“You keep smiling,” Vladimir Kudla said. “Whatever moves you make, make them so he knows we are still confident and we adore him no matter what happens.”

The role of tennis parent is among the more difficult in the sport. While fully invested in the outcome, emotionally and financially, tennis parents are powerless to help. And at the top ranks of the game, the role is often performed badly.

Arlington’s Kudla, 20, is among the lucky ones.

He started playing tennis at 7 mainly because his elder brother, Nikita, played. But his parents recognized his natural gift and found him proper coaching — first in Burke and then, as he progressed, at the Junior Tennis Champions Center in College Park.

“We don’t have a clue how to play tennis,” said Vladimir, an architect. “Thank God I didn’t start to teach him!”

At every stage, Denis was the one demanding more.

His mother got permission to pick him up from elementary school one hour early so they could race from Fairfax to College Park, where she’d wait through his two-hour practices, drive him home while he slept, then wake him for dinner and homework.

In ninth grade Denis started home-schooling, commuting on his own to practice in College Park via Metro, lugging two racket bags bigger than he was and changing trains twice during rush hour.

“The schedule he had was ridiculous,” said Nikita, 25. “But he loved every minute. The only time he got nervous was when our father told him that if he didn’t keep doing well in school, he’d had to give up tennis.”

Southern Cal was among the schools eyeing him, but Kudla chose to turn pro at 16 with his parents’ blessing.

Lucy Kudla explains that she dreamed, as a child, of being a ballet dancer. She started lessons in her native Ukraine at 5. Her coaches said she had promise, but her mother wouldn’t hear of it.

“Still it’s a passion,” Lucy said. “As soon as I hear music, I’m dancing in my mind.”

It was her way of explaining how she felt about Denis’s decision to turn pro while his friends prepared for college.

“I could see that Denis had a dream since he was little,” Lucy said. “So for me — it’s me. It’s like I’m dancing.”

If Kudla’s match against Groth was a variation on dance, Kudla was Fred Astaire, performing with a variety of steps, while Groth was slam-dancing.

There was no speed gun on the Grandstand Court, but Groth blasted one serve so hard that the electronic scoreboard flickered off when the ball hit the back fence.

Asked to guess the speed, Kudla said, “They were numbers I didn’t want to see.”

As Groth unloaded, Kudla varied the pace, deliberating hitting softer to coax errors from the Aussie.

“Smart shot,” Vladimir said when Kudla tried a lob that sailed just long. “A good idea.”

As the match unfolded, Kudla’s rooting section in the stands expanded.

It included John Callahan, 56, who lived on the same cul de sac when the Kudlas lived in Fairfax. For years he endured the “Thwack! Thwack!” of tennis balls bouncing off the plywood that Denis tacked to the family garage. It invariably started up just as Callahan returned from his early shift and laid down for a nap.

“The whole neighborhood heard it!’ Callahan said with a chuckle. He sported a Lacoste shirt, along with Denis Kudla, who’s sponsored by the company, and every other Kudla on the grounds.

The extended family also included Frank Salazar, the JTCC coach who developed him. It included friends from Arlington, strangers who knew only that he was an American and others who simply felt that the combustible Groth, who flung his racket in disgust after one double fault, simply wasn’t as likable.

The first set, settled by a tiebreak, turned on a single point.

After Kudla was broken for the first time in the match early in the second set, things unraveled quickly.

“What is the point to play tennis in front of people?” Vladimir mused as his son stepped up to serve, trailing 2-4. “The drama. You cannot save your kid from that. You cannot save your kid from being upset, or even from being humiliated.

“If that’s what your kid wants to do, you just keep quiet. He’ll figure it out.

Kudla was broken again, which put the match in the Aussie’s hands.

Groth served out the victory and unleashed a triumphant roar as the Kudlas looked on.

A man they didn’t know came over. “You have a terrific son!” he said.

He was followed by another. “He’s doing just fine,” the man offered with a smile.

Said Vladimir: “You decide you want to be a professional tennis player, pain follows. My heart is bleeding. But he’ll figure it out.”