The big four will face big challenges early at Wimbledon.
Venus Williams was at fault in a Florida car crash in which a 78-year-old man later died.
Hall of Famer believes one of Big 4 will win Wimbledon, but if they falter he picks five players who can prevail.
"All it takes is to have one wrong move, lose your footing," three-time Wimbledon champion said.
Mac doubles down, ESPN colleagues call argument "ridiculous" and "irrelevant."
Hall of Famer says it's time tennis stops players from using toilet breaks as gamesmanship.
The Swiss duo helped draw record crowds to Perth in 2017.
