PARIS -- Coco Vandeweghe boarded a Lufthansa flight from the U.S. to Marrakech in April for the Grand Prix SAR La Princesse Lalla Meryem, the season's only WTA tournament in Africa. She stepped onto the clay court for her first-round match against Myrtille Georges and quickly took a 4-1 lead in the first set. And then she sprained her ankle while sliding on the clay, injuring herself so badly that she was forced to retire from the tournament and also withdraw from her next scheduled tournament the following week in Portugal.

She called her travel agent to change her flight plans, checked out of her hotel and returned to California. She estimates that the travel costs for her and her coach (whose expenses she also was responsible for) were at least $4,000.

And her winnings in the Marrakech tournament?

$530.

Coco Vandeweghe is among those players who need to worry about the cost of travel. Matthew Stockman/Getty Images

"Tennis is not a cheap sport and outside of the Grand Slams, I don't think there is enough money in regular tournaments. The payout to cover expenses is not even remotely close to the reality of things," Vandeweghe said. "The money hasn't changed much and the cost to fly anywhere has risen to enormous levels. How are we supposed to compete with that with the job we have? Especially now that they're putting a lot more tournaments in China.

"It's crazy."

For those at the top, tennis can be a very lucrative sport, what with the prize money -- the French Open will pay $2.25 million to each winner -- and the many endorsement and commercial opportunities. But not everyone is Maria Sharapova with her own high-end, gluten-free candy. And the expenses can be exorbitant.

For example, Vandeweghe's uncle, Kiki, didn't make LeBron James money playing in the NBA in the 1980s and early '90s ($5 million over seven seasons), but it was a substantial amount back then. More importantly, he didn't have to pay for his flights, lodging or coaches, either.

Nor did his teams frequently need to fly to France, Spain, Italy, Germany or Australia.

Bethanie Mattek-Sands did not play in this year's French Open because of injuries, but last year her travel itinerary included flights from Phoenix to Australia, Thailand, India, Doha, Dubai and Malaysia, back home, then on to Miami, Indian Wells, Charleston, Stuttgart, Madrid, Rome and then Paris and Wimbledon. And that was just the first six months of the year.

Her husband, Justin, often travels with her and he estimated their annual travel expenses are easily $125,000. Other players agreed that's a realistic figure for Americans. "It's anywhere from 60 grand to 100 grand per person," Alison Riske said. "And if you carry a coach with you, it's going to be the same amount. It's a pricey endeavor, that's for sure."

"It costs a LOT," said Sloane Stephens' mother, Sybil Smith. "Especially in the juniors. Same amount of tournaments, same amount of traveling. But you're not making money in the juniors. And you're doing that for so long to make it to the senior level, it's so expensive."

Indeed. A Washington Post feature on Francis Tiafoe estimated roughly $400,000 has been invested in the 16-year-old's career through scholarships at the Junior Champions Tennis Center and aid from the USTA. That's necessary because his parents simply can't afford the expenses ... or even go see him play in tournaments. They are immigrants from Sierra Leone who work multiple jobs just to make ends meet. His father even lived in a spare storage room at the tennis center in College Park, Maryland, where he was a maintenance worker.

"Without sponsors, I definitely would not be here," Tiafoe said. "I thank them a lot. USTA helps me out a lot, the Tennis Center. I can't thank them enough. Without them I wouldn't have a chance to be here at all. I will say thank you to them a million times. Hopefully, I can keep getting better and they can keep paying for my travels."

Riske says she planned to go to Vanderbilt but then a family friend with his own business generously volunteered to cover the travel expenses for her and her sister (who coached her then) on the pro tour. "He was definitely my angel," she said.

The general view is that players ranked in the top 100 make enough money to cover their expenses and also earn a comfortable living. Mattek-Sands, currently ranked No. 84, had a good 2013, earning nearly $500,000. But with injuries, she has only played enough to earn $89,000 this year (though she hasn't had to travel quite as much, either).

"I think she's had some pretty good years," Justin Sands said at last year's French Open. "We're very comfortable. You would love to be pulling in the stuff that Roger Federer and Sharapova do but it's all what you make of it. You live within your means as best you can. It is an expensive sport. There are those weeks where you're out in the first round and you're spending money on coaching and traveling and all that -- it takes its toll. But it all comes out in the end."

At least it does when you win enough.

Something too often overlooked these days is that players aren't just trying to beat an opponent -- they're also trying to earn a living. By melting down against Sharapova after winning the first set 6-1 Tuesday, Garbine Muguruza not only cost herself a trip to the French Open semifinal, but $261,000, as well.

"I would be lying if I said I didn't think [after a match], 'That's an extra so-many grand right there,'" Riske said. "But that's exciting. That's part of what drives you, too. Obviously, that's what makes the world go round and to continue on the tour, you need the finances. It's nice to get a win here and there in the bigger events."

Ask Kiki Bertens. The Dutch player entered Roland Garros ranked 148th in the world and had earned just over $600,000 in five years on the tour. Then she advanced to the fourth round here, earning $170,000. "It's pretty good for me, I think," she said.

Tournaments do generally pay a per diem to cover hotel costs and tennis players are a bit like the George Clooney character in the movie "Up in the Air," collecting as many airline miles and hotel points as possible. Naturally, they prefer the nicer hotels. "You want to be comfortable and ready to compete," Riske said. "You don't want to stay at the Super 8. It's an investment for sure."

When Andrea Petkovic was starting out, though, she couldn't always afford a hotel. She remembers staying at a youth hostel in England for one small tournament.

"Next to me were 25 boys celebrating something, I don't know what," Petkovic said. "They kept singing English songs for the whole night. And I had to play next day at 10:00 in the morning.

"Well, I lost."

Well, that is what happens when you can't afford to stay at a Holiday Inn Express.

It costs Bethanie Mattek-Sands well over $100,000 to travel on a yearly basis. Matthew Stockman/Getty Images

The lesser tournaments give lucrative incentives to get the marquee names to show up, but the low-level players have to scrap for everything they can get.

"Especially the people below 100 -- they have to find tournaments to play in and not every tournament goes well," Vandeweghe said. "If you're making $500 a week and you're paying at least $2,000 to come to Europe and back and you don't get past the first round, you've just lost $1,000. And that's just the plane. Not counting food or cab to the airport or anything."

For such players, she says, "Money is always going out of your pocket."

Vandeweghe lost in the second round here, but the good news is her trip to Roland Garros still was far more lucrative than her trip to Marrakech. By reaching the second round, she earned roughly $57,000 -- more than 100 times what she earned in Marrakech -- bringing her year's winnings to more than $125,000, or what some consider the break-even point for annual expenses. She is 22, has risen to No. 91 and the future looks bright indeed.

But if this tennis thing doesn't work out, she could always become a travel agent what with her experience on the tour.

"No, I want no part of that," Vandeweghe said. "I call my agent around midnight his time and say, 'I need a flight. Tomorrow! Get me out of here! I need a flight to the next tournament!' Especially when I was in Marrakech. 'I need to get home. I need to get X-rays. I need to get my ankle treated. I need to find out what's really going on!' And he's like working on it, trying to finagle it, figuring out the best way to get me back to the U.S.

"He hates my guts sometimes."