(CNN) -- World No. 1 Tiger Woods lamented a "rough day" after equaling the second-worst score of his professional career on Saturday.
The American carded a seven-over-par 79 as he posted a triple bogey and two doubles in his opening nine holes at the Memorial Tournament, to be 16 shots off the lead as he struggled in the windy conditions.
"It was a rough day," the defending champion told the PGA Tour website. "It was tough out there from beginning to end."
Woods had seemed in good shape to end his five-year wait for a 15th major title at this month's U.S. Open, with four wins already in 2013, but his form at Muirfield Village in Ohio has been his worst this season -- carding 71 and 74 in the opening round of a tournament he has won five times.
"It's just one of those things where I'm sure I'm not the only one who struggled out there," said Woods, playing his first tournament since his public spat with Sergio Garcia -- who was accused of a racist remark after saying he would serve Tiger "fried chicken" in response to a question about their argument at last month's Players Championship
"The conditions were tough -- when I missed it cost me," Woods added. "I caught the wrong gusts at the wrong time, made a couple bad swings and all in all it just went the wrong way."
Starting on the back nine, Woods posted 44 by the turn -- his worst effort on the PGA Tour. He hit back with three birdies but then dropped two more shots, including a bogey at the last hole.
"We didn't hit that many bad shots starting out the day and the next thing you know we are quite a few over par," he said. "It was a tough day. I tried to fight back on the back nine, just didn't quite materialize."
World No. 2 Rory McIlroy also struggled in the third round, undoing his good work having earlier completed a weather-delayed 69 that meant he made the halfway cut.
The Northern Irishman carded 75 -- three better than his opening 78 -- as he ended the day tied for 64th, two shots ahead of Woods but 14 behind leader Matt Kuchar.
Kuchar posted his second successive round of 70 to claim a two-shot lead from fellow Americans Kevin Chappell (68) and Kyle Stanley (73).
Kuchar is in form after finishing second at last week's Crowne Plaza Invitational, while he won the World Golf Championships-Accenture Match Play Championship in February.
Halfway leader Bill Haas dropped to a tie for fourth with Matt Jones and 2010 Memorial winner Justin Rose of England after slumping to 76.
Meanwhile, Matteo Manassero stayed in contention for a second successive European Tour title despite faltering at the Stockholm Masters on Saturday.
The 20-year-old Italian, who last week became the youngest winner of the tour's flagship PGA Championship, carded one-under 71 to be tied for third in Sweden -- four shots behind leader Mikko Illonen of Finland.