Scott, Australia's top golfer at No. 7 in the world rankings, warmed up for this week's U.S. Open with a share of second place last weekend at the Booz Allen Classic, where he was the 2004 champion.
He's won nine titles on four continents since turning pro in 2000, but his best showing at one of golf's four Grand Slam tournaments was ninth place.
'He's overrated in terms of winning the big championships,' Thomson was quoted as saying on the Australian Broadcasting Corp. Web site on Tuesday. 'He hasn't got near winning [a major] up to now. I wish he would win something really big and put it all beyond doubt.'
'It's overtime, overdue. I think this year is a crunch year for him. He must win, this month the U.S. Open, or next month, he must win the British Open -- and then we can say he's achieved what he promised.'
Thomson, who was voted to the World Golf Hall of Fame in 1988, won the British Open five times, including three consecutive titles from 1954-56.
Scott, who will be 25 next month, won the Booz Allen Classic and the Players' Championship in 2004 and started this year with wins at the Johnnie Walker Classic and the Nissan Open.
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