Originally Posted by BobbyOne
...achieved in an age of life (31) when Rosewall could not enter the GS tournaments.
Finally I have deciphered the meaning here, which is not clearly expressed in the incomplete sentence in English as used.
Laver won his Grand Slam at the age of 31. When Rosewall was at the same age of 31, he could not enter the slam tournaments.
Rosewall was 35 when he could enter all four slams in 1969.