To add insult to injury Manley - who was second overall at that stage - followed up his ace by taking septuple-bogey 11 at his next hole.
The 34-year-old had only minutes earlier revelled in his rare hole-in-one moment when his tee shot to the 161-metre third took a couple of bounces before dropping in the middle of the cup.
Manley celebrated by high-fiving his caddy, playing partner and members from the crowd and even went over to take a closer look at the silver Mercedes, parked behind the tee, that he believed he had just won.
But soon after the world number 346 was to be informed the car was only available for a hole-in-one on the final day of the tournament, meaning he had missed out.
To make matters worse Manley imploded at the next hole.
The Aberdare golfer, who confirmed his European Tour card in qualifying last week, sent his approach shot into a greenside bunker as the calamity began.
His recovery shot flew across the green where a couple of hacks saw the strokes wrack up.
Eventually he landed a chip on the green where he three-putted to card an 11.
Manley eventually finished his eventful day with a one-over 72, before taking to Twitter to try and convince Mercedes to reconsider the decision to deny him the car.
He retweeted a post from one of his followers, which read: "Come on @MercedesBenz please give @stu_manley the Merc for his Hole in One. #MercForManley".
Manley admitted he had suffered through an emotional day, after which he was remarkably still left in a tie for eighth.
"It's the highest high and then the lowest low I've ever experienced on a golf course," he told the PGA Tour website.
"I thought the car was mine, and with the crowd, all the hype, I was just buzzing. The adrenaline was pumping so much, I could have flown to the green.
"Then I found out about the car, and go and have an 11. I kept asking my caddie, 'How many shots is that now?' I actually thought it was a 10 but I was not going to argue, because my head was pretty fried at that point, to be honest."
Australia's Jason Day leads the individual leaderboard on nine under, which also meant he also led the team standings, alongside Adam Scott, on 11 under.