A grieving Morgan Hoffmann carded a six-under 66 to take a one-shot lead after the first round of the Arnold Palmer Invitational on Thursday.
The 25-year-old American upstaged the bigger names at the Bay Hill Club and Lodge, holing four birdies and an eagle to sit atop the leaderboard.
Hoffmann's grandmother died on Thursday morning, and his response was to grab his first lead on the PGA Tour.
A group of five are only a shot back - Americans Jason Kokrak, Kevin Na, Ken Duke and John Peterson joined by Englishman Ian Poulter.
Adam Scott's solid start to this campaign continued with a four-under 68 to open the PGA Tour event in Florida.
World number one Rory McIlroy managed a 70 to be tied for 32nd in what is his final appearance before April's Masters.
Hoffmann's day started with birdies at 10 and 12 before another at the fourth.
His round improved on the sixth hole, where he holed from the bunker for eagle, before a birdie to finish the day.
Kokrak and Poulter both had eagles at the 16th, while Peterson went through bogey-free.
Alongside Scott at four under are 10 other players, including Swede Henrik Stenson.
Irishman Padraig Harrington and Scot Martin Laird are joined by Americans Brandt Snedeker, Billy Horschel, Harris English, Keegan Bradley, Hunter Mahan, Matt Every and Ben Martin in a tie for seventh.
McIlroy had two birdies on the front nine in his round before a bogey at the 16th, where he found the water with his second shot.
He recovered to post a birdie at the 18th to complete a solid first round.