Premise: Mark Knowles (born 4 September 1971) is a former tennis player from the Bahamas, specialising in doubles tennis. He has won a number of Grand Slam tournaments, most notably partnering with Daniel Nestor. At various times between 2002 and 2005 he was ranked World No. 1 in doubles. He is a five-time Olympian.
Hypothesis: Mark Knowles won Grand Slam tournaments by himself.