Question: How many Grand Slam singles titles did the tennis player, who defeated Hana Mandlíková, during the 1988 Australian Open – Women's Singles, win?
Sentence (from "Williams sisters"): The Williams sisters are two professional American tennis players: Venus Williams (b. 1980), a seven-time Grand Slam title winner (singles), and Serena Williams (b. 1981), twenty-three-time Grand Slam title winner (singles), both of whom were coached from an early age by their parents Richard Williams and Oracene Price.
Relevant evidence: No