The 29-year-old Scot will be hoping to advance to the final for a first time after tasting semi-final defeat three times previously and with nine-times French Open champion Rafa Nadal out through injury, Murray's chances have greatly improved.
"Maybe Andy's best chance to win the French ever could be this year," said seven-times major winner McEnroe, who is working as a commentator in Paris.
"I don't know if he's going to be able to keep this up, so to me he has got his best shot ever.
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"He has arguably been coming up against the three greatest guys who ever lived. So he has gotten a lot better and he can take pride in that. He can still add on a couple of majors.
"I think he is doing everything he can. I don't know him that well, certainly not enough to see his day-to-day. But Andy's had an incredibly consistent record in the slams."
Murray has won eight of his 15 encounters against Switzerland's Wawrinka.
Serbia's Djokovic, who like Murray has never won the French Open, takes on Austrian Dominic Thiem in the other semi-final on Friday.
(Reporting by Ian Rodricks in Bengaluru; Editing by John O'Brien)
