If you look at photos of Hideki Matsuyama at past events, you can see the same two-tone Submariner in many different images. not only is this a pretty good indicator that it is actually his own personal watch (and not one that was loaned to him by a brand representative to be seen wearing at a specific event), but since some of the photos are pre-September 2020, it also confirms that Matsuyama’s Submariner is the old ref. 116613LB and not the current production version, as the new generation of Submariner watches, did not exist at the time some of the photos were taken. 
While some Rolex replica ambassadors can wear a number of different watches, Hideki Matsuyama seems to wear only his two-tone Submariner and you will be hard-pressed to find photos of him wearing any other watch. Similarly, Tiger Woods wears his personal Deepsea Sea-Dweller the vast majority of the time, and while both Rolex ambassadors may wear whatever model they want, both Woods and Matsuyama seem to choose their own personal watches when they hoist the trophy.
Hideki Matsuyama may have been wearing his two-tone Rolex Submariner when he won the Masters on Sunday, but those watching the tournament may have also spotted another Rolex watch on the wrist of Matsuyama’s caddie, Shota Hayafuji. Unlike Matsuyama, who only wore his Rolex Submariner during the awards ceremony (most golfers don’t actually wear watches when they play), Hayafuji wore his replica Rolex all weekend, and many different spots could be seen on his wrist throughout the tournament.
Those with a keen eye may have noticed that Shota Hayafuji was wearing a 40mm Rolex Yacht-Master with a slate-colored dial. The platinum bezel, slate dial, and bright turquoise seconds hand are all features of the Yacht-Master, and Yasuji Hayao’s watch was seen several times when he extended his hand to congratulate Matsuyama after a good shot.
