At the beginning of last week, with the position of World #1 at stake in both men’s and women’s draws, few would have suggested that Elina Svitolina and Alexander Zverev would be your Rogers Cup 2017 champions. The two young stars have long been tipped for tour success, and they proved any doubters wrong this weekend with dominant, straight sets wins over their more decorated opponents in Caroline Wozniacki and Roger Federer, respectively. Their wins also had significant repercussions for the race to become World #1, on both the men’s and women’s tour. Here’s all you need to know:

The women’s tour

After a disappointing Rogers Cup where many (myself included) tipped her for the title, Karolína Plíšková will be looking to bounce back in Cincinnati, with the likes of Simona Halep and Angelique Kerber hot on her heels for the coveted #1 spot. Plíšková lost to Caroline Wozniacki in a close quarter-final in Toronto, and a win in “Cincy” would see her cement her position as #1, and add to the 931-point gap between her and Halep. The Romanian will also be wary going into this week’s competition. Her half of the draw does not feature Venus Williams, Garbine Muguruza, and Jelena Ostapenko. However, it does feature Svitolina, who beat her comprehensively in their Rogers Cup semi-final, 6-1 6-1.

The Western and Southern Open is classed as a “Premier 5” WTA tour event. As a result, there are only 900 points at stake. With Pliskova defending her title, though, that means that there are five players who can earn the World #1 ranking next Sunday. The scenarios are complicated and depend a lot on what each other does, but these are the five women who can earn the spot and the #1 seed at the US Open. Halep (needs at least semifinals, depending on Pliskova), Svitolina (needs at least semifinal, depending on others), Wozniacki (needs a title and Halep to lose before the final), or even Angelique Kerber (needs a title and early losses by Pliskova and Halep). We could be in for a wild week in Cincinnati.

The men’s tour

The Rogers Cup 2017 saw the rise of two #ATPNextGen stars in Denis Shapovalov and Alexander Zverev, who threw the race to become World #1 wide open. Shapovalov’s victory over Nadal in the round of 16 stunned the world, and it meant that the much-anticipated head-to-head battle between Federer and Nadal would be put on hold for at least another week. Likewise, Zverev’s 6-3 6-4 win over Federer in the final was a surprise, but Federer fans need not fear, because the Swiss maestro could leapfrog Nadal and become World #1 this week.

As it stands, Nadal is a mere 195 points behind the injured Andy Murray, who has withdrawn from Cincinnati in an attempt to get fit for the US Open. Federer lies 410 points behind Nadal, so a title for him this week would guarantee him the top spot. However, Murray is defending 600 points in Cincinnati, so both Federer and Nadal are guaranteed to pass him this week. If Nadal loses early, then Federer can earn the #1 seed with a semifinal appearance (but if Nadal wins even two matched, Federer will need to reach at least the final). If Nadal reaches the semifinals or better, Federer will need a title to take the top spot. The Swiss maestro complained of slight bruises and pains after his final defeat to Zverev in Montreal yesterday. This will determine how well he does, but it appears as though the momentum this week is with Nadal to reclaim the #1 spot. Both players will be looking to build on their successful years even further, and the prospect of seeing them battle it out over the #1 spot for the next few weeks could just become the best thing to happen to men’s tennis in the past couple of years.