Serena Williams is not a Miami-Dade County voter. Neither is Roger Federer nor Rafael Nadal. But they, and many of the world’s other top tennis players, will have an eye on the Nov. 6 local election, where a ballot measure could extend the lease of the Sony Open and approve $50 million of tournament-funded upgrades to Key Biscayne’s Crandon Park Tennis Center.

The “Park Partnership” referendum, No. 238 on the ballot, stipulates that the upgrades would come at no cost to taxpayers. The entire project will be paid for with tennis center and tournament revenues and private funds. The plan can move forward only if a two-thirds majority of voters vote “Yes.”

Last March, the Sony Open drew 326,000 people, nearly 20 percent of whom were tourists who booked 15,000 hotel room nights. The tournament features the top 90 men and women in the sport and has 7,000 hours of global TV coverage spanning 180 countries.

The Sony Open is considered the “Fifth Slam,” behind Wimbledon, the U.S. Open, French Open and Australian Open. But tournament organizers said the facilities, which have not been upgraded since 1994, need a facelift to keep up with new state-of-the-art tournaments around the world. Without the upgrades, they fear the event would eventually move.

Several top players weighed in:

Federer: “It is difficult to believe that the Sony Open could be forced to leave Miami. The event has a long history there, and it is certainly one of the favorite stops on tour for the players.”

U.S. Open and Olympic champion Andy Murray, who has a condo on Brickell Avenue: “I love Miami and spend several months of the year here training at Crandon Park. The fan support here is always incredible, and the event is one of the best on the tour.”

Serena Williams: “The Sony Open is one of the most glamorous events on the tour. A lot of what makes it great is the diversity of Miami, and the fan support at the event is wonderful. It would be terrible if the tournament had to move.”

Novak Djokovic: “Miami is one of my favorite places to visit. … It was the first Master’s Series Event I ever won so I will always have fond memories of Miami. I hope the event is able to stay there.”

Nadal: “Miami is like a second home for me. It would be very sad if the Sony Open was forced to leave.”

Juan Martin del Potro: “For the South American players, the Sony Open is one of the most important events.”

Maria Sharapova: “The Sony Open and Miami are synonymous with each other. I can’t imagine the tournament not being in Miami. I hope it is able to stay because it is one of my favorite places on tour.”

Venus Williams: “As a South Florida resident, I can’t imagine the Sony Open not being here. This is one of my favorite events, and I know it means a lot to community.”

The Sony Open’s proposed park updates include new green spaces, shaded areas, landscaping with native plants and trees, and show courts with comfortable seating. Miami-Dade County will continue to own and operate the Tennis Center, so the public would be able to use the facility for 49 weeks of the year.