Gilles Muller and Bernard Tomic have pulled out of the $100,000 Nordic Naturals Challenger, organizers informed the Register-Pajaronian on Friday morning.
Muller, the most successful tennis player from Luxembourg and former No. 21 in the world heading into retirement after this year, and Tomic, who is two years removed for being ranked No. 17 in the world, were slated to headline the 31st annual ATP Challenger Tour stop at the Seascape Sports Club in Aptos.
American Michael Mmoh, a 20-year-old ranked No. 121 in the world, will fill in one of the vacancies. Mmoh, a Bradenton, Florida native, is fresh off a quarterfinal appearance at the Los Cabos Open in Los Cabos, Mexico.
Qualifying rounds are set for Saturday and Sunday at 9 a.m. and 9:30 a.m., respectively.
Main Draw matches will begin on Monday.
Last year’s runner-up, Liam Broady, will be back in the mix, as well as quarterfinalist Dennis Novikov.
Broady, a 24-year-old from Great Britain, is ranked 177th in the world, while Novikov, a 24-year-old from just over the hill in San Jose, enters ranked 206th.
Novikov, who was born in Moscow, Russia, last year lost to eventual champion Alexander Bublik.
Drian King, Quentin Halys and Noah Rubin also return from last year’s main draw.
King, 26, hails from Barbados and is ranked 179th in the world. He was bounced in the second round last year.
Halys, 21, is a French prodigy who lost in the second round last year but has since teetered on a top-100 ranking.
He enters ranked 142nd after being ranked as high as 102nd earlier this year.
Rubin, 22, is an American from New York that has shown promise since turning pro in 2015. He lost in the first round last year, but has had a strong 2018, winning a pair of Challenger titles and earning a wild card into the main draw of the French Open.
Rubin will also be competing against his compatriots in the 2018 US Open Wild Card Challenge, which provides the winner of a five-week point challenge with a singles main draw wild card into the US Open later this month.
Rubin was tied for second in the latest available standings, but Ernesto Escobedo and Tommy Paul, whom will compete in the main draw, were both hot on his heels.