Masters champion Jordan Spieth conceded he has "some work to do" at the RBC Heritage heading into Friday's second round.
Spieth posted two bogeys and a double-bogey in his three-over 74 in the first round of the PGA Tour tournament on Thursday, as just about everything went wrong for the 21-year-old at Hilton Head Island.
With Matt Every and Graeme McDowell both carding 66 to claim a share of the lead, Spieth ended the opening day in South Carolina eight shots off the pace.
"Well, I didn't drive the ball well, didn't particularly strike my irons well," he told the PGA Tour's website.
"My chipping and putting wasn't there. It was just an off-day."
Spieth added: "I've got to play well [on Friday] to be able to play the weekend here.
"And it's certainly something I want to do."
Spieth is the first Masters champion to front up at the RBC Heritage since Zach Johnson in 2007.
Although many might blame his display on Thursday on an Augusta hangover, Spieth is not interested in excuses.
"I like this course a lot," the Texan said. "I didn't expect myself to shoot six under or eight under in the first round. But I'm still riding enough momentum and playing well enough to shoot an under par around here.
"[Matt] Kuchar is older than me, and he's at the end of a four-week stretch. And he kicked my butt today, so I've got some work to do."