He is the only/first player who has won GS twice
He is the only player who has won GS twice.
He is the first player who has won GS twice.
Are both sentences grammatically valid? If the tennis player is still active, can I use the present perfect tense in both instances?
"He is the only player who has won (a? the?) GS twice" is grammatically correct. The second sentence should read as follows: "He is the first player to win (a? the?) GS twice." My uncertainty about adding an article ("a" or "the") is based on my not knowing what a "GS" is.