Path to defence: Defending champion Jonas Blixt starts strong at The Greenbrier Classic
Blixt fired a six-under-par 64 to sit atop the leaderboard at the end of day one at the Old White TPC in White Sulphur Springs, West Virginia.
The Swede - winner of last year's tournament by two strokes - holed eight birdies and two bogeys as his title defence opened on the right note at the PGA Tour event.
Blixt is a stroke clear of eight players tied for second spot, including Americans James Hahn, Jason Bohn, Joe Durant, Chris Kirk, D.A. Points, Patrick Rodgers and Jim Renner, plus New Zealand's Danny Lee.
"I talked to my caddie about it and on the first tee," said Blixt, who tied for second at the Masters earlier in the year.
"There was no wind, so I just said to him, 'I'm going to be really aggressive today.'
"He was like, 'Yeah, I like that. Just go out there and make as many birdies as possible.'"
Completing the top 10 is South Korean Sang-Moon Bae, who ended the day at four under alongside Americans Michael Thompson, Steve Stricker, Kevin Na, Troy Merritt, Chris Stroud, Pat Perez and Chad Collins.
Speaking ahead of Thursday's opening round, Blixt admitted he is more likely to get nervous about missing the cut than when challenging for a title like last year.
But the 30-year-old helped ease those nerves with a blistering start to his campaign in West Virginia, birdying six holes on the back nine.
Blixt started with a birdie at the 10th hole before repeating that feat at the 12th, though he bogeyed the 13th.
The Swede responded immediately, birdying the next hole before adding another three in succession from the 16th to the 18th.
Blixt also added another two birdies on the front nine as he surged clear of the American contingent.
Meanwhile, Masters champion Bubba Watson opened with a two-under 68 - a round that included five birdies and three bogeys.