Other tennis contenders include Muguruza, Wozniacki, Halep, Nadal and Cilic. (AP)

Voting for the 2018 ESPY Awards is now open, and a crew of tennis players are nominated.

Most notably, Sloane Stephens is up for Best Breakthrough Athlete, against NBA and NFL players Donovan Mitchell, Ben Simmons and Alvin Kamara. 

Stephens won her first Grand Slam at the 2017 US Open, just two months after coming back from foot surgery. She has since won the Miami Open and appeared in the French Open final, getting her ranking up to a high of No. 4 in the world. 

 

2017 US OPEN CHAMPION #GRATEFUL

A post shared by Sloane Stephens (@sloanestephens) on

Stephens is also nominated for Best Female Tennis Player, alongside the other reigning Slam winners: Garbine Muguruza, Caroline Wozniacki and Simona Halep. 

 

A dream come true!! @australianopen champion and new world #1 ????????

A post shared by Caroline Wozniacki (@carowozniacki) on

Men's tennis has only two reigning major champions, so joining Roger Federer and Rafael Nadal in the nominations for Best Male Tennis Player is Marin Cilic, who made the final of Wimbledon in 2017 and the Australian Open in 2018. 

Cilic, coincidentally, is looking increasingly like one of the favorites for this year's Wimbledon. He won the Queen's Club title on Sunday by beating Novak Djokovic in the final. Federer, meanwhile, was handed a loss in the Halle final by Borna Coric. 

Federer is also nominated for Best Record-Breaking Performance, for his eighth Wimbledon title. He'll have to beat out Aaron Judge, Tom Brady and Diana Taurasi. It's arguable that Nadal's performance at Roland Garros was more impressive, but maybe breaking your own record doesn't count? 

The ESPYs will be held on July 18.