For years, you could see the sturdy, grimacing kid from Mallorca coming, but in 2003, he actually arrived.
"Man, I am sorry for beating you," Nadal told Moya.
"It's normal, the first of many times," Moya, seeing the future, responded.
Nearly 15 years later, and for the first time since he was a child of 4, Nadal will have a new coaching voice and a second opinion. It will be Moya, who won the 1998 French Open and last year helped coach Milos Raonic to the world No. 3 ranking.
Previously, Rafa's uncle Toni was Nadal's only coach. But after winning 14 Grand Slam singles titles, the past two years have been filled with injury and disappointment for Nadal.
Can Moya help Nadal recover his signature, massive and muscular game? Is it possible we'll see a ludicrous 10th title this spring at Roland Garros?
None of our experts was willing to go quite that far. But they all believe Moya has the ability to help make Nadal competitive again.
Of course, it's difficult to fall off the floor. Nadal's past six major results: second round, third round, first round, third round, DNP, fourth round.
Paul Annacone, a Tennis Channel analyst, had a knack for bringing aging champions across the finish line. He was with Pete Sampras when Sampras won his 14th and final major at the 2002 US Open. Annacone coached Roger Federer for three years, from 2010-13, and guided the 30-year-old to two ATP World Tour year-end titles, a return to the No. 1 ranking and a seventh Wimbledon championship.
"I like the decision," Annacone told ESPN.com. "They've been friends for a long time, and Carlos has been a role model. But one of the hardest things to measure is the impact of a coach, particularly to great players.
"The most important thing a coach brings that has been in that environment is a 3 or 4 percent improvement in something -- at the most important time. That's the difference between playing for a major title and going out in the fourth round."
Nadal was relatively healthy in 2015, but the best he could do at the Grand Slams was a pair of quarterfinal berths, at the Australian Open and French Open. The 2016 clay-court season began well enough, with back-to-back titles in Monte Carlo and Barcelona, but after winning his first two matches in Paris, Nadal withdrew before the third round. It was his shortest stay ever at Roland Garros, and the culprit, a left wrist injury, forced him to pass on Wimbledon.
The daunting physical demands of his hard-hitting game have now forced Rafa to miss at least one Slam in four of the past five seasons. The nagging wrist injury forced him to shut his season down in October.
After a lengthy recuperation and six weeks of fitness work back home in Mallorca, Nadal reappeared a few weeks ago in Abu Dhabi. The Mubadala World Tennis Championship isn't an official ATP-sanctioned event, but it usually features a strong field. Impressively, Nadal beat No. 3-ranked Raonic, No. 10 Tomas Berdych and No. 11 David Goffin to win his fourth title there.
A few days later, Nadal surfaced in Brisbane, Australia, clutching a koala bear.
"I am happy to be back on the competition again," Nadal said to the Brisbane press. "I prepared myself as much as possible in terms of physical performance on the court. Just excited to compete again. Abu Dahbi was a good start. I need to continue that way."
Which he did in his first formal event of the season in Brisbane, advancing to the quarterfinals, before losing to Raonic in three sets.
Brad Gilbert, who will be part of ESPN's coverage of the Australian Open from Jan. 16-29, coached Andre Agassi, Andy Roddick and Andy Murray. The cagey former professional insists Moya will be extremely helpful in the area of strategy.
"He was just with Raonic, who played all these guys, and he'll be there all the time," Gilbert said. "I think he'll help him in the areas of serving and forehand accuracy. Also on his second serve.
"Maybe mix up some of the patterns he's been employing over the years."
Mary Carillo, also a former pro and a Tennis Channel analyst, similarly predicts merely modest changes.
"Since Rafa was a boy, he watched him and trained with him. I think Moya has always been on his team, so I don't know that this is some grand, epic change. Moya recognized early that the master had been exceeded by his own student."
Annacone also predicts no major philosophical changes.
"Carlos won't teach Rafa to serve and volley," Annacone said. "What he can say, based on his vast experience, is 'Here's why I think it would work for you.' Those are experiential values Rafa can buy into. You have to figure out how to sell it. Great players are so great. You better be pretty darn sure you're selling something that works.
"I give Rafa and Uncle Toni a lot of credit for adding Carlos. To hear it differently from Carlos Moya, or someone else, is hugely beneficial."
Five players -- Federer, Sampras, Chris Evert, Steffi Graf and Serena Williams -- have won a single Grand Slam seven times in the Open era. Nadal has already collected nine titles at Roland Garros, equaling Martina Navratilova's Open era record at Wimbledon.
Can he push that total to double digits?
"He's still very viable on the clay," Carillo said. "He's had a rotten time at Wimbledon, following with the US Open. I'm anticipating he'll play a smart schedule and try to get himself in position for a 10th at Roland Garros."
Perhaps more importantly, does Rafa still believe he can challenge at the Grand Slams?
"I cannot tell that, because as I say before, I cannot predict the future," Nadal said. So I don't want to say things that I cannot say -- because I don't know.
"The only thing I can say is, if I am healthy, I believe I can do that. If not, I will be at home fishing."