Richard Green set a challenging clubhouse target of 18 under par during the final round of the Portugal Masters.
But the Australian could have been even better placed - he reached 20 under at Oceanico Victoria Golf Course before dropping a shot at the 16th and three-putting the last for another bogey.
Overnight leader Pablo Martin had also reached 20 under early in his round but double bogeyed the seventh and had seven holes remaining with a simple equation - play them under par and win a third European Tour title.
The contest looked a two-horse race as third place was occupied by Robert Karlsson and Francesco Molinari - both of whom were in the clubhouse at 16 under.
Molinari had earlier carded his second 62 of the week but was left frustrated by rounds of 74 in his first and third rounds.
"It wasn't easy out there," he said. "It looked easy today, but I don't know, it's been such an up and down week that I don't know what to say.
"I mean, two 62s in one week is quite amazing, but if you shoot two 62s in two days, you should probably win the tournament. 20 under for two rounds is quite something.
"I think I just need to rest because obviously the game is there, but probably the mind is not there all the time."
