Tiger Woods at a loss to explain first-round flop at Isleworth

Tiger Woods was at a loss to explain his latest struggles after an error-strewn return to competitive golf on Thursday at the Isleworth course he knows like the back of his hand.

The former world number one sputtered to a five-over 77 in the opening round of the Hero World Challenge that left the tournament host last in the 18-man field.

"I shot 80 a bunch of times here actually," said Woods, who estimates having played the course 500 times before. "Usually when it's a cold north wind and it's about 30 (Fahrenheit, -1 Celsius) out. But not like this. Today was weird."

Playing in warm sun and in front of a friendly gallery on his former home course, Woods struggled with his tee shots and short game in a round that left him a staggering 11 strokes back of tournament leader Jordan Spieth.

It was far from how Woods had planned his first competitive round since shutting things down in August due to back issues.

Woods, 38, foreshadowed his round on the first tee as he stood in front of a massive sculpture of a charging bull before sending his first shot through the fairway of a dogleg right and just short of a pool in a former neighbor's yard.

Looking slimmer and less muscular than in recent years, and playing with zero pain, Woods had trouble controlling the ball. He did not hit his first fairway until the sixth.

His worst hole came at the par-four eighth.

Again he came close to an unscripted visit in his old neighborhood when his tee shot soared left, carried over trees and bounced off a metal fence fronting a home.

With a limited backswing, Woods tried to punch out but his ball ricocheted off a tree. As he walked away he backhanded his club against the fence, sounding a clank of frustration on the way to a double-bogey.

The pattern changed at the turn.

After finding only two fairways in his five-over 41 on the front side, Woods hit all seven fairways on the back nine.

Unfortunately, his short game deserted him.

"It certainly is surprising that I could hit chips that poorly," admitted the 14-times major winner, who flubbed three of them.