The Aussie was walking off the 16th tee -- his seventh hole of the second round -- when he got into a dispute with caddie Matthew 'Bussy' Tritton, and the looper left Allenby holding the bag.
Not literally, of course, for Australian trainer Vern McMillan was standing outside the ropes and took over the bag.
This wasn't the first time a caddie has quit on Allenby in the middle of the round, but it might have been the first time he didn't see it coming. He sensed some tension, especially when he said Tritton ignored his request for a 5-wood off the 16th tee.
'He started walking off the tee. I said, 'What's wrong?' And then he started whining at me,' Allenby said. 'For two days everything has been fine. He just said, 'You don't want me to caddie any more. You want me to leave, don't you?' I said, 'No, I don't.' And then he just left.'
It wasn't too much of a disruption. Allenby, who opened with a 74, birdied the 16th hole, then played the front nine in 33 to shoot a 68. That left him tied for 46th in the 65-man field, but it was a strong showing considering that he is No. 24 in the playoff standings and is trying to nail down his spot in the Tour Championship.
Allenby figures it would take a miracle for him not to make East Lake, but he's leaving nothing to chance.
As for the caddie leaving him?
'That's golf,' he said. 'That's the way it is. It's not the first time, and it won't be the last time, either. I definitely played some pretty good golf after that.'
Perhaps his most famous incident came at St. Andrews in the 1995 British Open, when Michael 'Sponge' Waite was on the bag.
'He picked up my bag over his head and threw it about 100 yards,' Allenby said. 'I had to carry it myself up to the green, but he was waiting for me when I got there. He said, 'I'm a professional, I'll finish the round.' And I birdied four of the last 10 holes.'