French Open champion Justine Henin-Hardenne's coach, Carlos Rodriguez, says if his disciple doesn't take a more aggressive approach into Wimbledon, she'll have no chance at winning the one Grand Slam she hasn't captured.
Toni Nadal, Rafael Nadal's equally intense coach and uncle, has much the same to say about his French Open champ.
Scraping the clay off the heels of one's red-stained tennis shoes and putting the imaginary spikes on grass has never been easy for Roland Garros champions, and never will be.
But winning the French Open and Wimbledon back-to-back has been done before, and is possible if the player has the three necessary ingredients: standout conditioning to survive the brutal six-week period between the French Open's start and Wimbledon's final; transferable weapons that are equally dangerous on both surfaces; and enough self belief that you're up to the historic task.
As Bjorn Borg, the last player to win the French and Wimbledon back-to-back three years running, once said, "You have to find it. No one else can find it for you."
Henin-Hardenne has all the ingredients to win, but because she is susceptible to the virus that took her off the tour much of last year, whether she can sweat through a month and a half of hard-core tennis is questionable.
But she does have the components: power off wings, speed, an excellent serve, terrific touch at the net and a biting slice backhand. She reached the final in 2001, when she was still just a babe in the woods and was bullied by Venus Williams.
Two years ago, after she won her first Roland Garros title, she was beat up in the Wimbledon semifinals by eventual champ Serena Williams. She was never able to impose her high variety of styles as Serena played about as well as she ever has on the lawns and blitzed her with a searing attack. On that day, Henin-Hardenne looked too small and meek to make much of an impact.
Rodriguez believes part of that defeat was Henin-Hardenne's choice of tactics.
"Justine needs to serve and volley more on grass," Rodriguez said after Henin-Hardenne trounced Mary Pierce for the Roland Garros title. "She has to go to the net more. Everybody knows it. She knows it, too. But you can't repeat it to her every day. She has the qualities to win the tournament, but hasn't put the game in place to do it yet.
"Players like Serena, [Maria] Sharapova, Venus and [Lindsay] Davenport are bigger and naturally stronger than Justine is. But she has let those players take the game to her. Now she has to take the game to them."
Henin-Hardenne says she is a better player now than she was two years ago, and it could be argued that of the aforementioned fearsome foursome, only Sharapova is improved and should really be feared. The defending Wimbledon champion handed Henin-Hardenne her only loss of the season this year, in the quarterfinals of Miami on hard courts. Serena has played only a handful of matches since injuring her ankle in early April, Venus had a disastrous Roland Garros and hasn't won a significant title in 14 months, and Henin-Hardenne hasn't lost to Davenport since 2002.
Women's tennis is different from men's when it comes to switching from dirt to grass. Steffi Graf with her huge serves, fearsome forehand and wicked slice backhand went back-to-back at Roland Garros and Wimbledon four times. Martina Navratilova did it twice. Chris Evert did it once, as did Henin-Hardenne's bitter rival, Serena, in 2002.
So why not the Belgian, who certainly volleys better than either Graf or Evert ever did and is a whole lot faster than Navratilova? Even two-time Roland Garros finalist Martina Hingis who's the same size as Henin-Hardenne won Wimbledon, and her serve and forehand were a shadow of Henin-Hardenne's.
Most of Henin-Hardenne's success this year will depend on her head. She will ultimately decide if she's willing to make the necessary adjustments to beat the elite power players when she reaches the second week of Wimbledon.
"She has to play better grass-court tennis and come into the net a lot more," Rodriguez said. "She also can't be thinking that it's the only Grand Slam she hasn't won, because if she does, after the first or second round, she'll be out. The pressure is already there. She can't put more on herself."
There's a great deal more pressure on four-time Grand Slam champion Henin-Hardenne than there is on the 19-year-old sensation Nadal, because almost no one believes it's possible for a male to go back-to-back on clay and grass anymore. The last man to do so was the remarkable Borg in 1980. Plenty have come close: Ivan Lendl reached the final at Wimbledon twice after winning in Paris. Stefan Edberg reached the Roland Garros and Wimbledon finals in 1990, and Jim Courier did the same in 1993. After he pulled off his Parisian miracle in 1999, Andre Agassi nearly won Wimbledon, but was numbed in the final by his nemesis, seven-time winner Pete Sampras.
But since then, Roland Garros has largely become a clay court/slower court specialist's paradise. Of the last four men to win the Roland Garros title Gustavo Kuerten, Albert Costa, Juan Carlos Ferrero and Gaston Gaudio only Ferrero made it to the fourth round of Wimbledon the same year he reigned in Paris.
On clay, there is plenty of time to set up points and impose yourself while sliding round in the backcourt. On grass, the ball stays very low, dies quickly and if you prefer sliding, you'd better bring a crash helmet. It's nearly impossible to dig deep into the low-cut blades, and you could find yourself flying headlong into a some duke or earl's lap.
But if Lleyton Hewitt, who is the same height as Nadal and nowhere near as strong, can win the Wimbledon title, why can't Nadal? The same analogy could be made with Agassi, who wasn't nearly as quick as Nadal or hit as hard off the forehand when he won the Wimbledon crown in 1992.
But those two men have one huge weapon that Nadal doesn't have: a blazing return of serve that muted the serve-and-volleyers. The Spaniard doesn't have that he prefers to drive the ball into the center of the court to get himself dug in for rallies. That's death against serve-and-volleyers.
Moreover, his vaunted forehand is hit with a severe western grip, and it's much harder to come over the skidding balls on grass with that style than it is on clay. And while Nadal can turn from defense to offense in a flash and has an amazing array of passing shots, he's primarily a defensive player. That style does not win major grass-court titles.
"I can't challenge for the title," Nadal said when asked about his Wimbledon chances. "I want to improve. I like a lot to play in grass. I know it's not my best surface. It's a little bit fast. I need to improve some things in my game [to] play better in grass the serve and the volley."
At least Nadal is committed to getting better on the surface. He is playing two grass-court warm-up events in hopes of arriving at the tournament in decent form. Like Hewitt, he's a tremendous competitor, which will play in his favor. But as coach Toni Nadal says, the learning curve this year is far too great.
"We are not going there looking to win," Toni Nadal said. "Rafa has to focus on getting used to the grass and adapting his game to it. But [Roger] Federer is a much better player on it. We still have a long way to go. Maybe in a couple years it will be different, but for now, we can't think of winning both in the same year. But Rafa will fight hard, I can guarantee that."
Matthew Cronin, the managing editor of Inside Tennis magazine, is a regular contributor to ESPN.com.