Spain's Albert Ramos-Vinolas returns the ball to Canada's Milos Raonic during a fourth-round match Sunday. (Miguel Medina/AFP/Getty Images)

When nine-time champion Rafael Nadal departed the French Open last week because of a left wrist injury, he vowed to return to his favorite tournament. Nadal’s shot at winning a 10th title at Roland Garros is dwindling. It’s not merely that he turns 30 Friday, his troublesome knees, shaky confidence or his now suspect wrist.

Nadal shares one natural advantage with many of history’s other tennis greats: He is left-handed. But over time, larger forces have conspired to blunt the unsettling spins, angles and serving trajectories that lefties traditionally imposed on the majority population.

String and racket advances, surface changes, strategic shifts and the two-handed backhand have leveled the court to a large degree.

“It’s still an edge,” said Martina Navratilova, the winningest southpaw ever, “but not as much as it used to be.”

Left-handers once were the sport’s closest thing to a caste of disrupters.

Wielding wooden rackets and gut strings on slicker courts against mostly one-handed opponents, lefties relied on their offbeat spins and paces, all coming from the opposite direction, to vex opponents. Righties more accustomed to forehand-to-forehand cross-court rallies had to rethink their patterns of approach shots and serving strategies.

Perhaps most troubling of all, they were vulnerable to a lefty wide serve to the backhand side in the ad court, often at crucial junctures in a game such as 40-30 or break point.

Consequently, lefties won a lot.

Navratilova, Rod Laver, Jimmy Connors, John McEnroe and many others accumulated gobs of Grand Slam titles in the last four decades of the 20th century.

Lefty winners of majors, the sport’s highest prize, began to dip in the 1970s for men and in the 1980s for women. For instance, left-handed males won 12 of 40 majors from 1970 to 1979 but just three from 1990 to 1999.

Left-handed women’s Grand Slam champions peaked in the 1980s, largely because of Navratilova, then dropped off precipitously.

In the past two decades, just two lefties have won major titles: Petra Kvitova at Wimbledon in 2011 and 2014, and Angelique Kerber at this year’s Australian Open.

What happened? The game changed.

Space-age materials, larger heads and innovative designs made rackets lighter and more powerful. Polyester strings amplified topspin over slice.

Ball-rotation levels are 50 percent higher than in the 1990s, according to John Yandell, a Yale-educated researcher that studies stroke production using high-speed video on his website

“There’s now a uniform, heavy-groundstroke ball that has negated net rushing and neutralized the former effects of backspin,” Yandell said.

Surface speeds slowed and homogenized, neutralizing some serving and side-spin benefits.

“In the 90s when the courts were icy, lefties were more dangerous,” says lefty Bob Bryan, who with his twin brother, Mike, a righty, has collected a record 16 Grand Slam doubles titles.

Basic point-winning strategies also shifted from serve-and-volley tactics to baseline bashing.

“The game became much more linear, more groundstroke-based, more hit-through-the-court,” California-based author and tennis historian Joel Drucker said.

Most of all, two-handed backhands hijacked the sport.

The vast majority of today’s pros use two hands on what was once a less powerful, vulnerable wing. Now backhands are weapons.

Righties today can snuff the forehand-to-backhand cross-court conundrum posed by lefties. They likewise can punch back wide serves to the ad side as never before.

Consider Nadal’s nasty, high-spinning forehand. It has caused nightmares for Roger Federer by forcing the one-handed Swiss to strike his backhand out of his natural hitting zone (Nadal leads their rivalry 23-11). Double-fisted players such as Novak Djokovic and Andy Murray can step forward and meet the ball on the rise.

“Djokovic now takes that shot and hits a laser, flat backhand back cross-court, and Nadal has no answer for that shot,” said lefty Tom Gullikson, a former U.S. Davis Cup captain now working with the USTA’s Player Development program.

The number of left-handed ATP players ranked in the top 100 has remained relatively stable the past 40 years, ranging from about 15 to 25 per season. Their rate of tournament wins, however, has dipped.

Lefties won 16 percent of all tournaments from 1986 to 1995. That fell to roughly 13 percent the following decade and a tick lower (12.8 percent) from 2006 to 2015.

When it comes to bigger trophies, the only left-handed man to win a Grand Slam title besides Nadal in the last 15 years is Goran Ivanisevic at Wimbledon in 2001.

The WTA generally has fielded fewer lefties in the top 100 and counts just six today. At this week’s French Open, no female left-handers advanced past the third round for the first time since 2010.

The last lefty women’s winner in Paris was nine-time Grand Slam champ Monica Seles in 1992, almost a quarter-century ago (and she played double-fisted off both wings).

Some wonder if Nadal, a 14-time major winner, should be left out of the discussion because of his extreme playing style, particularly his lasso-like forehand that finishes high above his head.

“Nadal is not unusual because he’s a lefty,” Navratilova said. “He’s unusual because of how he hits the ball.”

Many of today’s players echo the sentiment that left-handedness is of waning, or no, benefit.

“It’s not an advantage, honestly,” said veteran Spaniard Feliciano Lopez, a lefty ranked as high as No. 12.

Righties describe facing left-handers as a minor inconvenience rather than a strategic headache.

“No different,” American Jack Sock said when asked if it had factored into his third-round defeat to unseeded left-hander Albert Ramos-Vinolas of Spain.

Others believe the lefty downswing is cyclical.

They say fewer win majors because the top of the sport has been dominated by righties like the Williams sisters, who have won 28 grand slam singles titles since 1999, or Federer, Djokovic and Murray, who have won 30 titles since 2003.

“Probably in the future, there will be more,” Nadal said last year. “I believe it is more about coincidence.”

None of it makes sense to American Taylor Townsend, 20.

A southpaw with an outside-the-box playing style, Townsend believes she has a huge advantage over her righty peers. But it doesn’t necessarily come from how she strokes the ball.

“You think differently,” she said.