Novak Djokovic dominated rival Rafael Nadal at the start, then held off a comeback attempt to win 6-1, 6-4 at the Paris Olympics in the second round Monday, the 60th — and likely last — head-to-head matchup between the two tennis greats.Djokovic claimed 10 of the initial 11 games, with Nadal nowhere near the skilled and ever-hustling version of himself that won a record 14 French Open trophies on the same red clay at Roland Garros that is hosting Summer Games matches. Instead, Nadal was diminished, showing every bit of his 38 years, and looking like someone who might be ready to head into retirement after playing only sparingly the past two seasons because of a series of injuries, including hip surgery.Then, suddenly, the indefatigable Nadal got going, making a push to turn this contest competitive, which surely no one — least of all Djokovic — found too surprising. Nadal captured four consecutive games in the second set, including a forehand winner to break to make it 4-all. He raised his left fist, drawing roars from a packed Court Philippe Chatrier crowd that repeatedly tried to encourage him with chants of “Ra-fa! Ra-fa!”And that's when Djokovic, a 37-year-old from Serbia, regained control. He broke right back, pointing to his left ear while walking to the sideline as if to taunt Nadal's supporters. Djokovic then served out the victory, before meeting Nadal at the net for a hug.Djokovic owns 24 Grand Slam titles, and Nadal 22, the two highest men’s totals in the century-plus history of the sport, both have been ranked No. 1, and no pair of men has played each other more often in the professional era. They are two-thirds of the so-called Big Three of men’s tennis, along with Roger Federer, who retired with 20 Slam titles. That trio enjoyed unprecedented success and prompted endless debates about which was the “GOAT” — “Greatest of All Time.”But Djokovic and Nadal are accustomed to meeting — and fans are accustomed to watching them — in the latter stages of events, including nine major finals. Not merely the second round. It happened that early this time because while Djokovic is the top seed at the Summer Games, Nadal’s ranking is outside the top 150 on account of a lack of matches.Part of Nadal's troubles Monday were caused by not being in tip-top shape. His right thigh has been taped up during these Olympics, where he is also competing in doubles for Spain with Carlos Alcaraz.And part of the problem, to be sure, was that Djokovic was, well, the best version of himself other than during that brief stretch in the second set, sliding along the baseline to get to everything, striking shots exactly where he wanted them, occasionally using drop shots to set up winners and force Nadal to run a lot. Djokovic wore a gray sleeve on his right knee, just as he did while making it to the final at Wimbledon three weeks ago. He tore his meniscus during the French Open in early June and had surgery in Paris.None of that mattered on this warm afternoon under a cloudless sky, with the temperature in the 80s Fahrenheit. Folks in the stands waved fans in an attempt to stay cool; both players wore cold white towels around their necks during changeovers.