He laid well back off the 18th tee and hit his approach from 185 yards to just inside 40 feet.
Casey, 40, was already in the clubhouse at 10 under, and Patrick Reed, playing in the group just ahead of Woods, could have forced a playoff with a closing par, but bogeyed instead to fall a shot back.
Woods and his massive following went dormant after an opening birdie to briefly share the lead.
Woods teed off on 10 and drained six-foot birdie putts at 12 and 13, and rolled in an 11-footer for another birdie at the par-four second hole.
American network NBC's audience for the third round, when Woods ensured he was in contention, were 181 per cent up on last year, making it the highest rating third round broadcast anywhere in the past 12 years. Today I wasn't quite as sharp as I would have liked to have had it, but I had a good shot at winning this golf tournament. "I played conservatively into the green because I wasn't as sharp as yesterday". "It was just one of those days where it was a half-club this way or that way".
A sensational 44-foot putt on the penultimate hole of his round was evidence that the Tiger of old is rising to the surface once again, as he told Sky Sports that he had relished his first big push to win a tournament on this latest comeback effort. This is the 70th time Woods is at or within one stroke of the lead after 54 holes on PGA Tour, according to the Golf Channel.
Woods will play next at the Arnold Palmer Invitational, beginning March 15 (AEDT).
He is an eight-time victor at Bay Hill, and the euphoria over his return is sure to reach even higher decibels.
"I was very thankful I made that putt on 17", Woods said. "A couple putts here and there and it could have been a different story". He is an eight-time victor at Bay Hill, and the euphoria over his return is sure to reach even higher decibels. Snedeker is streaky with his putter, but looks to be in form this week.
It all depends on what standard you wish to hold the 42-year-old legend to at this unusual point in his spectacularly unusual career.
On his way off the course, Woods stopped to sign autographs, showing a good deal more patience than he had during his heyday."Wow, what an awesome week. people, atmosphere, adrenaline, back nine on Sunday, man I've missed this", Woods later tweeted.
Reigning Masters champion Sergio Garcia enjoyed a good week as he prepares to defend his title early next month, the Spaniard finishing a shot further back at eight-under after matching Casey with a 65. Or you can think it's incredible that in such a short time he has clearly demonstrated he's essentially all the way back.
The crowds, of course, were out in full force to watch the world's most-popular golfer play. Of those, 18 players have won three or more times.
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