Kenny Perry believes he will face a battle to live up to his status as favourite heading into the John Deere Classic.

Since letting the Masters title slip from his grasp at the last in April, the world number four has largely struggled for form - even if it appeared to return with a vengeance during his victory at the Travelers Championship at the end of last month.

Four rounds under 70 at TPC River Highlands, including opening and closing efforts of 61 and 63, respectively, seem to fully justify the expectations surrounding the 48-year-old as he attempts to defend his crown in Silvis.

However, Perry, who failed to finish in the top 20 in five consecutive events before the Travelers Championship, admits he is far from confident in his game right now.

"I've been struggling, my golf game kind of went away," he said. "I've been searching, hitting a lot of balls.

"I think that's just me. I play great for two or three months in a row, and then I disappear for two or three months, and then I come back.

"It's just been the history of the way I play golf. I wish I could hang in the limelight longer and more often. It's just not the way I've been able to compete."

Perry will have to overcome a star-studded field, as well as his own self doubt, if he is to complete a successful defence, with the likes of US Open champion Lucas Glover, David Toms and Steve Stricker also highly fancied to be in the mix come Sunday afternoon.

"This is, without a doubt, the strongest field we've had since the tournament moved to TPC Deere Run (in 2000)," said tournament director Clair Peterson.

Perry, however, insists he can take comfort from his previous success in Silvis.

"When I go to a course I really enjoy, where I've had a lot of success, I do pretty well," he said.

"It was really disappointing for me this year to go to Colonial and Memorial, two of my bread-and-butter courses, and I had two average performances. That was tough.

"So we're at ground zero and I'm going to have to figure out something that's going to make me competitive."