Padraig Harrington claims it is only a matter of time before Rory McIlroy starts winning majors again despite rivals having caught him up.
McIlroy, the former world number one, has not added to his major tally since winning the Open and US PGA Championship back-to-back in 2014.
Harrington puts this down to increased competition in the elite game but has no doubt his fellow Irishman, who bids for a second Open title at Carnoustie this week, will eventually end his drought.
Speaking on his return to the scene of his 2007 Open success, Harrington said: "Rory's obviously played well this year and yet seems to be getting a lot of press saying he's not playing so well.
"Clearly, his career is now solely based on how he does in the majors. There seems to be no other yardstick for Rory, and that's probably the yardstick he uses himself.
"I think back in 2011 he had stolen a march on the field when it came to driving the golf ball, which brought tremendous confidence to his game. I think players have caught up. There are many players who drive the ball (to a) comparable (standard) and have certainly eaten into that advantage.
"It's just a tougher ask but the beauty for Rory is he's still very young, he's still very capable, and with patience those majors will come."
Fourteen-time major winner Tiger Woods will be in the field at Carnoustie, his first Open since 2015.
Woods has not won any of golf's most coveted individual tournaments since 2008, but his 2006 Open triumph at Hoylake came in similar hard and dry conditions to those which may prevail this week.
"He's good enough to win this championship, no doubt about it," said two-time Open winner Harrington, 46.
"I don't think he could play golf like the way he played in 2006 at Hoylake - but nobody else could have played the way he did. I suspect he couldn't play that way now. But he's definitely capable of winning this week. His game is good enough."
Harrington beat Sergio Garcia in a play-off to claim the Claret Jug at Carnoustie 11 years ago, a trophy he retained by winning at Birkdale the following year.
Now, a year after returning to Birkdale, he is pleased to be back at the scene of another past triumph.
He said: "I look forward to playing in every Open Championship. This one, like last year, I'm kind of coming back as a kind of defending champion.
"I know Jordan (Spieth) won last year but it does makes it a little more special when you're coming back in that circumstance."
Spieth hopes the imagination required to play bone-dry Carnoustie will bring out his best as he defends his title this week.
After returning yesterday a replica of the Old Claret Jug - which champions are allowed to keep for 51 weeks - Spieth spoke about how his game had become bogged down by technical thoughts during his busy stretch of tournaments in May and June.
But refreshed after three weeks off - spent partly on a beach holiday in Mexico - the American three-times major champion is ready to go again and upbeat about his prospects.
"I needed a break," Spieth said. "I was kind of dragging along and playing a pretty heavy schedule and I needed to get away from the game, which I did.
"Coming to an Open championship requires a lot of feel and imagination and I think that's what I needed a bit of in my game.
"I'd gotten very technical and very into making everything perfect instead of the way I normally play."