The second week of play is set to begin at the Australian Open, with 16 players remaining in the year’s first Grand Slam. There is plenty of action left, though, and there could be plenty of repercussions in the ATP Rankings.

ATPTour.com looks at the most glaring changes that could happen in the ATP Rankings based on what occurs in Melbourne.

Zverev Guaranteed To Reach No. 3, No. 2 A Possibility
No matter what happens the rest of the tournament, Alexander Zverev is guaranteed to at least match his career-high of No. 3 in the ATP Rankings. Since the German reached the third round last year, he only had 90 points to defend, whereas World No. 3 Roger Federer, as defending champion, is defending 2,000 points.

Zverev has already earned 180 points (90 more than in 2018) by moving through to the fourth round. And since he only trailed Federer by 35 points in the 14 January ATP Rankings, and the Swiss cannot gain points — even if he wins the title — Zverev will move to at least No. 3.

If Zverev reaches the final, he can potentially ascend to a career-best No. 2, which would make him the first player outside of the ‘Big Four’ to occupy one of the Top 2 spots since Lleyton Hewitt on 18 July 2005. By advancing to the championship match, Zverev would force Rafael Nadal to make the semi-finals or better. Nadal can guarantee that he will remain No. 2 if he reaches the title match in Australia for the fifth time.

Round-By-Round ATP Rankings Projection

Watch Zverev’s Road To The 2018 Nitto ATP Finals Title:

Federer Could Fall Out Of Top 5, As Low As No. 8
Since Federer is defending 2,000 points, the pressure is on for the six-time champion to make another deep run in Melbourne. If Federer fails to reach the semi-finals, he will fall outside the Top 5 for the first time since 20 March 2017.

A quarter-final showing would give Federer 4,780 points. As mentioned, World No. 4 Zverev is guaranteed to pass Federer, already guaranteeing himself at least 6,475 points. World No. 5 Juan Martin del Potro, who did not compete at the Australian Open, is locked in at 5,060 points, and World No. 6 Kevin Anderson, who lost in the second round, will have 4,845 points when the new ATP Rankings are released on 28 January.

The lowest Federer can fall after the tournament at this point is No. 8. If 2018 finalist Marin Cilic wins the title, beating Kei Nishikori in the final, and Federer loses in or before the quarter-finals, both Cilic and Nishikori will pass the 37-year-old Swiss.

Federer’s Round-By-Round ATP Rankings Projection

Cilic Could Drop From The Top 10
There could be a lot of movement in the ATP Rankings depending on the winner between Cilic and Doha champion Roberto Bautista Agut in the fourth. If Cilic loses, he will be in danger of falling outside the Top 10.

If Cilic advances no further, he will have 3,140 points on 28 January, which would at maximum place him at World No. 10, his lowest standing since 31 October 2016. If the Croat does go down in the fourth round, Borna Coric would be able to crack the Top 10 for the first time with a trip to at least the semi-finals. In the same scenario, if #NextGenATP Greek Stefanos Tsitsipas makes the final, he would also pass Cilic.

The following players would also surpass Cilic’s 3,140 points — should he lose to Bautista Agut — if they were to win their maiden Grand Slam trophy: Milos Raonic, Daniil Medvedev, Grigor Dimitrov, Pablo Carreno Busta, Roberto Bautista Agut and Lucas Pouille.

Cilic’s Round-By-Round ATP Rankings Projection

Tsitsipas Could Crack The Top 10
Reigning Next Gen ATP Finals champion Tsitsipas is into the second week of a Grand Slam for the second time, after also advancing this far at Wimbledon last year. If he should go on a dream run and claim the title in Melbourne, Tsitsipas would soar into the Top 10 of the ATP Rankings. A victory would send him to at least No. 8, while a Nishikori fourth-round loss would allow him to climb to No. 7.

How would the Greek make such an ascent? Based on Fabio Fognini (2,225 points) and Kyle Edmund’s (1,440) early losses, Tsitsipas is currently projected to reach a career-best No. 13 in the ATP Rankings. A title would give Tsitsipas — who was only defending 10 points from a 2018 first-round loss — 4,085 points on 28 January. That would put him past eliminated players Dominic Thiem (3,960), John Isner (3,155), Karen Khachanov (2,880), Fognini and Edmund, all of whom are currently ranked ahead of him.

Tsitsipas could potentially face Cilic in the quarter-finals (3,320), so he would pass the Croat as well. While Tsitsipas could potentially face Coric in the final, a championship-match appearance would give Coric 3,625 points, which would be less than Tsitsipas’ 4,085.

Keep in mind that during such a run, Tsitsipas would potentially have to face third seed Federer, sixth seed Cilic, second seed Nadal and World No. 1 Djokovic.

Tsitsipas’ Round-By-Round ATP Rankings Projection