A relentless Rafa Nadal thumped Kevin Anderson 6-3 6-3 6-4 to win the U.S. Open on Sunday, earning the Spaniard his second grand slam title of the season and 16th of his career.

While women's tennis produced three first grand slam winners this season, the old guard continues to reign supreme in the men's game, with Nadal and long-time rival Roger Federer sweeping the majors with two apiece.

It marked the fourth U.S. Open final and third title for Nadal but the first time without Novak Djokovic on the other side of the net.

The world number one was as brilliant as he was business-like, keeping the towering South African under constant pressure and denying him a single break point.

For 31-year-old journeyman Anderson, a grand slam breakthrough was not to be, his booming serve having no impact against a near-perfect performance from Nadal in front of a sold-out crowd at Arthur Ashe Stadium.

Nadal committed just 11 unforced errors in his 23rd major final.

Certainly the grand slam experience was all with Nadal but big-hitting Anderson showed no signs of jitters on the big stage of his first major final.

Nadal was quick to put his opponent's composure and service game to the test, and Anderson needed to fight off a pair of break chances at 1-1 and again at 2-2.

However, Nadal continued to apply the heat until his persistence was finally rewarded with a break to go up 4-3.

That was all he needed as he held serve then broke again to clinch the set with a cheeky drop shot.

Nadal continued to hammer away at Anderson, securing another break at 4-2 on the way to a two-set lead.

With the title within sight, Nadal locked in on the prize, breaking Anderson to open the final set.

The 32nd ranked South African continued to battle to the finish but with Nadal playing superb all-court tennis, there was no weakness for him to exploit.

In the end, he and the crowd could only watch as Nadal punched his hands into the air in victory, one finger raised to signal his status as number one in New York and the world.