The world’s top three golfers are all competing at the 80th Masters Tournament this weekend, and they are decked out in the country’s top three sports apparel brands.

Jason Day, Jordan Spieth, and Rory McIlroy, ranked Nos. 1, 2, and 3 in the world, are sponsored by Adidas, Under Armour, and Nike, respectively. And each brand has released new advertisements recently pegged to The Masters.

The ad spots differ in the approach they take, but they have one thing in common: They are extremely serious. Under Armour’s ad is part of its new “Rule Yourself” campaign, launched over the summer, and includes Spieth, the basketball player Steph Curry, ballet dancer Misty Copeland, quarterback Tom Brady, and swimmer Michael Phelps. The ads show how grueling and monotonous an athlete’s training schedule can be; each athlete is multiplied endlessly as they perform an action—for Spieth, it’s driving a ball.

Nike’s ad with McIlroy, released this month, follows a similar theme. He wakes up early, goes running, lifts weights, hits at the golf range and meets with the press. Then he does it again, and again, and again. It looks brutal. “Enjoy the chase,” the tagline reads.

Finally, the Adidas ad with Jason Day, who won his first major last year, is more stripped down and simple: Day, sitting down, narrates a 30-second clip about his ambitions. “Some might put their feet up, some might relax, pat themselves on the back,” Day says, “but that’s not me. Because the goal isn’t to win a major. It’s to win everything.” The campaign has the tagline “Geared for more,” and also features Dustin Johnson reflecting on his mistakes and Sergio Garcia lifting weights.

Spieth, McIlroy, and Day have been called The Big Three of golf, though many people add Rickie Fowler to that list and call it The Big Four. On YouTube, Under Armour’s ad with Spieth, Curry and Copeland has more than 2 million views; Nike’s new ad with McIlroy has nearly 2 million; the Adidas Jason Day spot has just 10,000.

So how effective are the spots? That question is the first topic in our new Sportsbook series (see video above). If you ask Brian Cristiano, CEO of New York ad agency Bold Worldwide, it is Spieth, who is just 22 and won two of golf’s four majors last year, that’s ahead of the other two in terms of fan recognition and branding power.

In other words, it helps to win.

But it also helps to be associated with the brand that, of these three, still enjoys an “underdog” appeal and has fewer marquee athletes in its stable, so it makes more hay with each of them. That’s Under Armour, which first signed Spieth right out of college in 2010, but last year re-signed him to a whopping 10-year deal, reportedly worth $200 million (McIlroy’s deal with Nike is thought to have the same terms), and at the precise right moment: just before he won The Masters, then the U.S. Open in the same year, and became world-famous in a rush. Under Armour’s re-signing of Spieth last year was arguably the smartest endorsement deal of the year. It began marketing him just in time for the launch of its first ever golf shoe.