After counting down the Top 5 WTA tournament matches and biggest WTA upsets of 2018, our year-end review moves to the best Grand Slam clashes of the season. At No.4 is stylish Hsieh Su-Wei's come-from-behind win over World No.1 Simona Halep at Wimbledon.

Top 5 Grand Slam Matches of 2018:
No.5: Cibulkova d. Kerber, US Open

After battling her way through a grueling Australian Open campaign, which ended with an intense, close loss to Caroline Wozniacki in the final, Simona Halep finally broke her Grand Slam duck at Roland Garros, prevailing over Sloane Stephens in the 2018 French Open final to win her first major title following three unsuccessful previous major finals.

The Romanian came into Wimbledon as the solid World No.1, and, having skipped the grass-court warmup events, looked to be in fine form in the opening rounds, moving past Kurumi Nara and Zheng Saisai without the loss of a set.

But lurking in the third round was the crafty Hsieh Su-Wei of Chinese Taipei, a former World No.1 in doubles whose mercurial singles career was back on the upswing. Hsieh had clawed back to the outer fringes of the Top 50 by Wimbledon, in part due to her fourth-round run at the Australian Open in January, which included a win over then-World No.3 Garbiñe Muguruza.

And yet, Halep had won their only prior meeting in Cincinnati in 2013; as the third-round tilt got underway, it appeared that the Romanian would emerge victorious once more. The match opened with five straight breaks of service, but Halep was first to settle her nerves, eventually taking the first set 6-3 in 45 minutes.

Hsieh was undeterred despite the loss of the opening frame, and used a litany of wily, unorthodox shots to stay with Halep in the second set. The player from Chinese Taipei, who hits with two hands on both sides, cracked open the set in its latter stages, reeling off the final three games to level the match at one set all.

Simona Halep (L) and Hsieh Su-Wei after their third-round match at Wimbledon 2018. (Getty Images)

By this point of the event, six of the Top 10 seeds had already been eliminated, so another potential upset, even of the World No.1, felt predestined. But Halep methodically took control of the final set, building a 5-2 lead. At 5-4, the Romanian held a match point on Hsieh's serve, and it seemed as though the top seed would dodge the upset bug for at least one more round.

But Hsieh bravely whacked a bold backhand to fend off the match point, allowing herself to level the match at 5-5. Turning the tables fully, Hsieh broke Halep to lead 6-5, and then served out the barnburner to evict yet another Top 10 seed from the topsy-turvy tournament.

Read the match report: Hsieh saves match point, shocks Halep at Wimbledon

By winning the last five games of the two-hour and 20-minute clash on No.1 Court, Hsieh notched a 3-6, 6-4, 7-5 victory to get her first win over a reigning World No.1 in her career. Both players broke serve seven times, but Hsieh was 7-for-12 on break points, while Halep rued converting only seven of a whopping 23 break chances.

Hsieh's first-ever win over a No.1 was another in her clutch of upsets over high-profile players at Grand Slam events, including a Top 10 win over Johanna Konta at the 2017 French Open, and wins over Muguruza and Agnieszka Radwanska at the 2018 Australian Open. The tag "giant-killer," though, isn't something that Hsieh ever sought out.

"I don't learn how to be giant killer," said Hsieh, during her post-match press conference. "I just want to feel free and enjoy the match. You know anything can happen on the court. You don't have big chance to win, because [the top players are] very good. So all I want to do is just go on the court and hit the shot and run every point and enjoy it."

"[Down] 5-2, against this big player on the big court, you could get smashed, a love game like this," Hsieh admitted. "It's not easy. I just try to run as much as I can, try to catch every ball."

The unconventional shot selection Hsieh deploys, which she cheekily called "Su-Wei Style" at the 2018 Australian Open, often surprises herself as much as her opponent. "Sometime can go good way, sometime not going good way," Hsieh stated. "[The] important thing for me right now is I need to keep calm and keep concentrate on the court."

"I was pretty concentrate on my match until the last point," Hsieh continued. "I was making the fall on my serve. I was saying, 'Oh my God.'" But winning changes everything. "Now I feel more relaxed," an elated Hsieh sighed.

Hsieh was unable to capitalize on her massive win in the following round, falling meekly to Dominika Cibulkova in straight sets, and she exited SW19 still seeking her first Grand Slam quarterfinal appearance. Hsieh lost to Cibulkova in the second round of the US Open later that summer as well, falling to 0-4 against the Slovak.

Nevertheless, Hsieh reached the second week at multiple majors in one season for the first time in her career, which propelled her back up the rankings. She capped off her season by winning the third WTA singles title of her career in Hiroshima, her first trophy at that level since 2012.

Hsieh clinched a season-ending ranking of World No.28 -- only the second season of her singles career which she finished in the Top 50 (she ended 2012 ranked No.25).

As for Halep, the remainder of the year was inconsistent. The Romanian never ceded her World No.1 ranking, finishing the season at the top spot for the second straight year. She also jumped right back into her winning ways after Wimbledon, blasting to the title in Montreal and extending her winning streak to nine matches by reaching the final at Cincinnati, nearly claiming that title as well.

But Halep suffered another shock defeat at a Grand Slam event in New York, losing her opening-round US Open encounter against Kaia Kanepi. Halep then dropped her opening matches in Wuhan and Beijing before calling it quits for the year due to a lower back injury, missing the BNP Paribas WTA Finals Singapore presented by SC Global in the process.

Halep, however, will open the 2019 season ensconced at World No.1, and, barring injury, she will attempt to grab the Australian Open title which eluded her at the very last minute in 2018.