Davis Love III headed six players on four under par after the first round of the St Jude Classic, with Padraig Harrington three shots back after a 69.
The 2012 United States Ryder Cup captain, who underwent back surgery in February and is looking for his first title since 2008, took a share of first place alongside compatriots Martin Flores, Glen Day and Harris English, as well as Stuart Appleby and Nathan Green of Australia.
The 49-year-old carded seven birdies against three bogeys, and saw room for improvement.
"You've got to be a little bit more patient and polished" - Davis Love III
"I still hit some bad shots," Love told pgatour.com. "At The Players and Memorial, I felt like I was playing better than I was scoring.
"I think it's rust. I'm excited to be back, and I'm anxious and I want to play better than I'm playing."
He added: "You've got to be a little bit more patient and polished. That's going to take some rounds of golf to get back."
Of the other leaders, Green was the most consistent, carding four birdies in a blemish-free round, English was helped by an eagle at the 16th and Flores was left to rue a double bogey at the par-three 14th.
Defending champion Dustin Johnson, who was playing alongside Love and Brandt Snedeker, looked set to take the outright lead at five under through six.
But three dropped shots in six holes from the ninth cost him and he ended up in a group of 11 at three under, which also contained the leading European challenger, Sweden's Peter Hanson.
Harrington was one under, alongside Englishmen Brian Davis and Greg Owen on a heavily congested leaderboard.
Ross Fisher was level par, as were Snedeker and Scotland's Russell Knox, while Gary Christian was three over.