The WTA World No.1 Ranking will be on the line at this year’s US Open. Can Serena Williams extend her stay atop the WTA Rankings and make history?

Only 21 players have occupied the No.1 ranking since the computer rankings were introduced in November 1975. Will we see a new player take hold of the No.1 spot for the first time in three years?

wtatennis.com breaks down the No.1 scenarios ahead of the US Open:

Serena Eyes Another Record: Williams enters the US Open as the WTA World No.1-ranked player, a distinction she has held since February 18, 2013. Through the two weeks at the US Open, Williams will extend her streak to 186 consecutive weeks, tying the WTA record for most consecutive weeks at No.1 held by Stefanie Graf (186 weeks, August 17, 1987 through March 10, 1991).

Williams currently holds a 190-point advantage over Kerber in the rankings. However, to break the record, Williams will need to at least reach the semifinals and possibly advance further. Williams is defending 780 points at the US Open as she advanced to the semifinals last year before Roberta Vinci stopped her run.

As Kerber progresses, though, Williams will need to advance further:

–   If Kerber reaches the quarterfinals at the US Open, then Williams will need to reach the final to have a chance at keeping the No.1 ranking.
–   If Williams wins the US Open, she will secure the No.1 ranking, regardless of any other results.
–   A championship match showdown between Williams and Kerber, the Top 2 seeds, would see the winner walk away not only with the trophy, but the No.1 ranking.

Williams’ ranking points have come from seven tournaments in the last 52 weeks – 2015 US Open (780), Australian Open (1300), Indian Wells (650), Miami (120), Rome (900), Roland Garros (1300) and Wimbledon (2000).

What Will It Take For Kerber To Become World No.1?: Angelique Kerber is bidding to become the 22nd player to hold the WTA World No.1 Ranking since the computer rankings were introduced in November 1975. The German came within one win of unseating Williams at No.1 in Cincinnati, but fell short in the final against Karolina Pliskova.

Last year, Kerber lost to Victoria Azarenka in the third round at the US Open and as a result is only defending 130 points in Flushing Meadows.

Kerber will have a 460-point advantage from the start of the tournament. An early exit would not necessarily prevent her from moving to No.1.

Kerber consistently has reached the final four at the tour’s biggest events with six finals appearances this year, winning the title at Australian Open and Stuttgart, finishing as runner-up at Brisbane, Wimbledon and Cincinnati. (She also reached the final at the Olympic Games, although that does not count towards ranking points). As a result, Kerber’s ranking has been on a steady incline after finishing 2015 at No.10.

Muguruza Also Has A Chance: One of three Grand Slam champions this year, Muguruza will need to reach the final at the US Open to have a chance of overtaking the No.1 ranking. Should she win her second Grand Slam title of the year, the Spaniard would take claim to the No.1 spot unless Kerber also reaches the final.

First Grand Slam Title Could Vault Radwanska To The Top: To have a chance at moving to No.1, Agnieszka Radwanska would need to win the US Open, although if she is able to win the title in New Haven this week, a run to the finals could potentially be enough.