Colin Montgomerie says the first five holes on Thursday will determine whether Tiger Woods' Masters comeback is a success.
The four-time champion announced last week he would play the season's first major - his first event since taking a break in February to improve his game.
Woods says he has worked "sun-up to sun-down" to prepare for his return, but Montgomerie is concerned a poor start at Augusta on Thursday could set back the 14-time major winner.
He told Sky Sports News HQ: “I worry. Three over after five [holes] tomorrow, game over. The first five holes for Tiger tomorrow afternoon is most important.
“If he can be level after five holes, game on. There’s a lot of pressure still, he’s put a lot of pressure on himself.
"His short game was phenomenal, a short game we’ve never seen before. How can you go from that short game to someone who can’t hit a green from 20 yards?
“Let’s hope he’s got that down and does make an effort to be in contention.”
The former Ryder Cup captain is tipping American Jimmy Walker as a potential winner but believes Rory McIlroy will triumph if he plays to his potential.
He said: “If Rory plays at his peak he will win. He is that far ahead of the pack. The pack are good - he is very good.”
Watch the Masters live on Sky Sports from Thursday to Sunday.