Osaka, Anderson, Thiem and the three most impactful matches of 2018

If Naomi Osaka had not beaten Aryna Sabalenka at the US Open, perhaps Serena Williams would have ended up with the championship. COREY SIPKIN/EPA-EFE/REX/Shutterstock

Great tennis matches occur every year, burned into our memory for any number of reasons. But there are also some that have a pivotal impact.

This is not to say that the matches below were the most memorable, the most dramatic or even the best. But they provided turning points in their own way.

Let's take a look at three matches from 2018 that ultimately led to significant storylines.

Naomi Osaka def. Aryna Sabalenka, 6-3, 2-6, 6-4
US Open fourth round, Labor Day

Osaka's breakthrough at the Grand Slam level was foreshadowed by her title at Indian Wells in March. But it was her win against Sabalenka months later in New York that changed the trajectory of her career, and arguably tennis history.

Had Osaka lost, Williams' final-round opponent would have been either Madison Keys, Sabalenka or Lesia Tsurenko. It's hard to imagine any of that trio denying Williams a record-equaling 24th Grand Slam singles title.

The match was played on a brutally hot day, at the new Louis Armstrong Stadium. Osaka took the first set, but Sabalenka charged back to win the second. Osaka then was granted the 10-minute heat break. It seemed to hurt more than help, but she recovered her poise after surrendering a break to fall behind 1-2. Osaka broke back and took charge the rest of the way.

Later, Osaka said she couldn't help but think of the memories from a heartbreaking loss to Madison Keys in the 2016 US Open, one in which Osaka had a lead, 5-1 in the third set, but squandered it. At the time, it would have been the biggest win of her career. Osaka did not want any such setbacks this time around.

The win marked Osaka's emergence as a dominant player. Her talent and poise rattled Williams in the final and might have contributed to the drama that ensued between the American and the chair umpire.

Kevin Anderson def. Roger Federer, 2-6, 6-7(5), 7-5, 6-4, 13-11
Wimbledon quarterfinals, July 11

Federer, toting an improbable 34-set Wimbledon winning streak into his match with Anderson, had not played outside Centre Court since the same stage of the event in 2015. Court No. 1 is windier because it is more open than the main stadium. But the breeze Federer found more troublesome on this surprising day in SW19 was coming off Anderson's racket as the 32-year-old No. 8 seed slugged it out with the eight-time champ.

The upset marked the turning point in Federer's year. While he won a major (Australian Open) and two other tournaments by June, the only title he would secure from mid-June on was in Basel, where Federer had eight previous wins in his hometown. Anderson's feat also set him up to play fellow John Isner. That seemingly interminable 6 ½-hour match between men with seemingly unbreakable serves, ultimately forced tradition-mad Wimbledon to embrace the fifth-set tiebreaker.

Federer roared through his first set with Anderson in barely half an hour. He also took the second set, even though Anderson had scored an early break. "I really tried my best to keep fighting," Anderson said. "I kept telling myself, 'I have to keep believing that today is going to be my day.'" Federer had a match point at 5-4 in the third set, but Anderson fought it off and turned the tide when he won the subsequent tiebreaker.

It was only the fourth time Federer had lost a match after being up two sets to love.

Dominic Thiem def. Rafael Nadal, 7-5, 6-3
Madrid Masters quarterfinals, May 10

True, the score line doesn't scream "great match!" This win by the then 24-year-old Austrian was more a case of a great performance -- and massive surprise -- with short-term as well as historic consequences.

The venue in Madrid is at a high altitude, so the balls fly faster and are harder to control. Thiem, who, like Nadal, prefers clay courts, took advantage of the conditions by taking risks. Eschewing his habit of playing from deep behind the baseline, he played up and was successful in forcing relatively swift points.

"I love it here in Madrid -- perfect conditions for me," Thiem told reporters after the match. "If I play normal against him, I lose probably. I played a little more aggressive, and it worked out very, very well, obviously."

The loss ended Nadal's 25-match, 51-week clay-court winning streak -- a run that began almost exactly a year earlier following a loss to the selfsame opponent. The upset also ensured Nadal, the defending champion, would lose enough rankings points to have to surrender the No. 1 ranking to idle Federer. At 36, Federer would add yet again to his legend as the oldest player to hold the No. 1 ranking.

In the small picture, one of the amazing things about this win was that just weeks earlier, in Monte Carlo, Nadal had beaten Thiem so badly that the Spaniard was moved to remark: "That is not a normal result against a player [like Dominic]." The comment was prophetic.

Also, had Nadal been able to add a sixth Madrid title to his collection, he -- not Federer -- probably would have ended up seeded No. 1 at Wimbledon. Being in the top half, Federer would not have faced the shutdown power of Anderson.

In the grander picture, the win was perhaps the confidence booster Thiem needed in majors. Long touted as a potential French Open champion, just weeks later, he rolled to the final of Roland Garros before falling to Rafa.