PARIS — For 2 hours 47 minutes, Alphina Tiafoe sat virtually stock still, clasping and unclasping her hands, kneading her fingers, examining her manicure — channeling all of her nervous energy, on some subconscious level, into her hands, which were in her lap and out of view of the players on Court 12.

At key moments, she would nod to her son. Or she would look directly at him, careful to put on a face that, without words, said, “Everything is going to be fine.”

But when Frances Tiafoe’s fortunes started sinking fast and his frustration boiled over — exhibited by the racket he slammed to the clay, his slumping shoulders and the groans of disgust — Alphina Tiafoe added her voice to the throng trying desperately to rally him as his first-round match at the French Open slipped away.

“Come on, Frances!” she shouted. “Do the best you can! You have nothing to lose! Keep trying!”

The challenges at the top level of professional tennis come in myriad forms: a physically superior opponent, a serve that isn’t working, a horrible call on a crucial point, soul-sapping fatigue heading into a fifth set.

But of all of them, among the toughest is being able to do nothing. That is the challenge of the tennis parent, who can look on from the stands and nothing more.

“It’s difficult. It’s very difficult, watching your son,” Alphina Tiafoe said after Frances Tiafoe, the tournament’s top-seeded American man, was upset in his opening match Monday by Filip Krajinovic, 6-2, 4-6, 6-3, 3-6, 6-0.

“My co-workers say, ‘Oh, you’re going to enjoy yourself!’ And it’s nice, going to different places,” she explained. “But when I sit there, you don’t know what’s going through my mind. I don’t want my son to get an injury. I don’t want my son to fall. A lot of things go through your mind — especially when it’s your child out there playing, no matter what age.”

For No. 32 seed Tiafoe, 21, the weight of expectations has increased each year since the Maryland native turned pro in 2015. They climbed higher still after he reached the Australian Open quarterfinals in January, which lifted him to a career-high No. 29 ranking. And they were ratcheted up further by last week’s splashy article and photo shoot in GQ, titled “Big Foe on the Come-Up,” that proclaimed him “the next great American hope.”

The article recounted Tiafoe’s unconventional path to the sport’s top ranks, as a son of Sierra Leone immigrants who learned to play at College Park’s Junior Tennis Champions Center, where his father was a maintenance man. The accompanying photo spread and video had him modeling haute, hipster couture — including a $2,250 Prada sweater, a $5,400 Fendi shirt and $1,450 purple Zegna pants. Tennis needs a younger look, the article argued, and Tiafoe, who radiated equal parts cool and joy, is the player to deliver it.

On Monday, there was far more interest in Tiafoe’s opening-round match than the cramped grandstands on Court 12 could hold. There were just a few rows of backless benches behind one baseline and one sideline, so spectators jammed into an adjacent walkway for a view.

There was no formal box for the players’ families — just a section of reserved seats on the second row. Alphina Tiafoe was the first of her son’s camp to take a seat, joined soon after by his physio, Bret Waltz; coach Zack Evenden, a Brit who played college tennis at Florida A&M; Octagon agent Kelly Wolf; Martin Blackman, general manager of U.S. Tennis Association Player Development; and coach Jose Higueras, who helped Michael Chang to the 1989 French Open title and nurtured the careers of many other top pros.

Krajinovic started aggressively, blasting shots with little margin and attacking the net, quickly putting Tiafoe 3-0 in arrears in the opening set.

“Once Frances gets his rhythm, he’ll be okay,” Blackman whispered as Alphina Tiafoe folded and unfolded her hands.

Behind Tiafoe’s team sat a trio of enthusiastic supporters of Krajinovic who had made the trip from Serbia. “Bravo!” they shouted with each point he won (or Tiafoe lost).

After they split the first two sets, Tiafoe started feeling queasy and threw up. He fell behind two sets to one, then came out blazing in the fourth — showing that he, too, could pull off tricky drop shots and blast forehand winners.

“That’s H-U-U-U-G-E!” Evenden shouted after one winner, and Tiafoe clenched a fist and turned to his mom as she beamed.

But he sailed a backhand long as he tried to serve out the set, and his mother clasped a hand to her face before quickly regaining her composure.

When he closed the set with an ace, leveling the match at 2-2, Alphina Tiafoe shot to her feet and put a hand over her heart. Then she turned to the American couple behind her who had been cheering on her son from the start and gave them a thumbs-up and a huge smile.

But Tiafoe’s rally proved as fickle as the few rays of sun on this gray Parisian day.

As his frustration built, the unforced errors mounted — 62 in all, against 42 winners. And there wasn’t a word from those who loved him that helped.

At the end, all that was left for Alphina Tiafoe to do, amid a defeat that no one anticipated, was to look toward her son and nod.

“I am always there to support,” she explained. “Good or bad, I’m always there to support. And when he finishes, I have to let him know I’m proud of him, and that he’s doing very well. Tomorrow is another day.”

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