Casey, who had played alongside Woods on day three and ended four shots adrift of Woods, snatched seven birdies in a closing 65 to win by a shot with a 10-under par tally on the Copperhead course.
The 40-year old Cheltenham-born Casey last won on the PGA Tour in capturing the 2009 Houston Open and in the intervening period has contested 155 Tour events before being handed the Valspar ‘Paint Brush’ trophy.
Casey has now won 18 times in his pro career and with 13 of those on the European Tour and the last being the 2014 KLM Open.
But in that time, much has changed in Casey’s life as he explained.
“My life has been a roller-coaster since I last won on the PGA Tour as I’ve been divorced, remarried and have kids, and I could not be happier today standing here as the winner of the Valspar,” he said.
“I played great golf. I managed to beat Tiger and I have not managed to say that probably ever in my career, so it’s been a really satisfying week.”
It had been an hour and 12 minutes from the time Casey completed his round before Casey was confirmed as the winner and with Casey anxiously glued to TV coverage first of Patrick Reed and then Woods.
Reed drew level with Casey after a birdie on 14 but let slip the opportunity to tie his English rival in bogeying the last.
All focus then turned to Woods who, after a birdie at the first, then parred 12 holes in succession ahead of having the crowd roar their approval in holing a snaking 43-foot birdie putt at the uphill par-3 17th to be now tied with Reed and one behind Casey.
Then at the last Woods stood over a 38-footer for birdie that would have tied Casey but left the putt short for an eventual par and finish tied with Reed.
Casey was naturally thrilled but also emotional and after revealing earlier in the week the passing the Saturday before and while he was competing in Mexico of Mary Culcoldruff.
“I didn’t think about it too much today. I thought a lot about it on Sunday in Mexico as she passed I found out Saturday night Mexico week,” he said.
“She had a long battle with cancer, too long to think about and the name is Mary and Ian, her husband, was there at the end and he’s a dear friend of mine.
“I’ll see him next week. He was one of my best friends when I joined Burhill, small club I’m still a member at in Surrey: His nickname is Nutta. I can’t explain it.
“But Nutta always looked after me and still does to this day and always welcome and watch me at Wentworth, Mary would always tag along and drove up to Scotland to see my very first victory. God, like eight, nine hours of driving or something to get from where they live up to Gleneagles.
“So, just, you know, heavy heart. One of those — unfortunately everybody, seems everybody has the same story I’ve got. Cancer sucks. It’s just rubbish.
“I actually didn’t think about it too much today. I think if I had thought about it probably could have been probably not right thing to think about playing. Afterwards just think about it now it’s more emotional now.”
Casey’s IMG manager revealed he was able to secure Casey a last seat on an Orlando departing flight to London on Monday afternoon US time) and with Casey to now skip this week’s Arnold Palmer Invitational to attend the funeral.
And after speaking of his sadness in returning home to England, Casey was thrilled to have denied Woods in what would have been first success in nearly five years.
“Tiger has made winning look easy for such a long time and it’s not and while I have won a few times in Europe but to win just my second PGA Tour victory is emotional,” said Casey.
“It’s emotional and as I have worked so hard for it, and the biggest thing was I lost a friend the Saturday when I was playing last week in Mexico so I played with a heavy heart and maybe that was the difference.”
Woods’ effort in a final day 70 continues to defy the doubters and just adds further bite in his gaol to claim a first victory in nearly five years.
“I felt very comfortable out there today though I didn’t feel that sharp with my iron game and I had to play very conservatively into the greens as I wasn’t as sharp as I was yesterday,” he said.
“It was just one of those day where I just kept getting a half-club and not quite get the full club.
“Then standing over my putt on 17 I thought to myself to just the right speed and I hit it would good dying pace even though it took forever to drop.”
Woods now heads to Thursday’s starting Arnold Palmer Invitational as favourite and in an event he’s won on eight occasions including back-to-back success in 2012 and 2013.