Tiger Woods carded a three-over 74 on his return to action at the Quicken Loans National after three months out injured.
Woods, who underwent surgery to repair a pinched nerve in his back in March, mixed four birdies with seven bogeys to finish well off the early pace in Bethesda, Maryland.
"The hard part was just getting into the rhythm of playing competitively," said Woods, who missed the first two majors of the year and lost top spot in the world rankings to Adam Scott.
"You play with your buddies all day for cash and stuff but it's just not the same. It's not the same as tournament golf, different level.
"(Here) adrenaline is rushing and I hit the ball further out here than I do at home. It unfortunately took a while to get the feel for it. That didn't start happening until midway through my front nine."
Woods, whose charity foundation is benefited by the event at Congressional Country Club, made an erratic start after teeing off at the 10th, recording five bogeys in his first nine holes to reach the turn in four-over 39.
He then dropped further shots at the second and third, where he found a greenside bunker with his approach, before finding his groove on a difficult layout to inch his way a little higher up the leaderboard.
Woods sank birdie putts from inside five feet at the fourth, seventh and eighth to come home in a one-under 35.
His overall statistics were something of a mixed bag as he hit nine of 14 fairways and reached 10 of 18 greens in regulation while scrambling a par only once in seven attempts when out of position.
"I made so many little mistakes," said the 38-year-old American, who won this tournament in 2009 and 2012. "But I played a lot better than the score indicated, which is good."
Asked how he felt physically after ending a three-month absence from the PGA Tour, Woods replied: "I had no issues at all. No twinges, no nothing. It felt fantastic.
"I unfortunately have been in my career on the sidelines enough, so it's always fun to come back out here and play against these guys, the best players in the world ... and see what I can do."
Australian Greg Chalmers was the pace setter on Thursday, birdies on his last three holes propelling him to a five-under-par 66, one clear of American Ricky Barnes and Swede Freddie Jacobson.