The 65-year-old five-time champion recovered from hitting his approach to the first into the Swilcan Burn with birdies on the sixth, ninth and 10th, but carded double bogeys on the 13th, 16th and 17th to come home in 41.
“I stunk up the joint today the way I played,” said the former Ryder Cup captain, who announced on Wednesday that next year’s Masters will also be his last. “Too many sixes on the back nine ruined my day.
“I had a little string of birdies going but made some unforced errors coming in... a little bit of brilliance but a bit of ugliness averaged it out.
“When I got it to a couple under par I knew the back nine was going to play a little tougher into the wind and I knew I had to hit some quality shots, and I didn’t. That was the disappointment. I didn’t follow up some of the good shots I hit in the middle of the round and finish the deal. I failed.”
Watson was grateful for the “extremely nice” support he received from the crowd, although he was not so enamoured by fans who wore masks bearing his likeness.
“Those are ugly masks,” joked Watson, whose round today will now be his last in a championship he first won on his first visit in 1975 at Carnoustie.
“I told them there are way too many wrinkles in those masks.
“It kind of scared me looking at those, like geez, look at those things; that guy is ugly.”