SAO PAULO — A Brazilian hospital says former No. 1-ranked tennis player Maria Bueno is being treated for mouth cancer and is in serious condition.

The 9 de Julho Hospital in Sao Paulo confirmed on Tuesday that the 78-year-old Bueno was being treated there. TV Globo, where Bueno has worked as a tennis pundit for many years, said her cancer was discovered last year and has now spread. It also said she has ruled out more chemotherapy but is being treated with immunotherapy.

Bueno is Brazil's best ever tennis player and won seven Grand Slam singles titles between 1959 and 1966, three at Wimbledon and four at the U.S. National Championships — as the U.S. Open was then called. She finished the year ranked No. 1 four times and also won 11 Grand Slam doubles titles — including all four in 1960 with two different partners.