A heated confrontation between PGA Tour veteran Robert Allenby and his caddie during Thursday's first round of the Canadian Open led to a contentious midround split, with Allenby having a fan jump in to caddie for his last nine holes.

Allenby and his caddie, Mick Middlemo, had a discussion before his fourth shot on the par-5 13th at Glen Abbey Golf Club in Oakville, Canada. According to Golf.com, Allenby had wanted a 7-iron, but the discussion focused on the 8-iron for the shot, which was about 150 yards out.

Allenby's shot fell short of the hole and into a creek. He tripled the hole.

Allenby, who finished the round with an 81, recounted the confrontation that followed to ScoreGolf.com:

"I said to him, 'You know this happens every week. This has happened for like the last three or four or five months. We keep making bad mistakes, and you're not helping me in these circumstances,'" said Allenby, 44. "And he just lost the plot at me. He just told me I could go eff myself.

"And I said, 'Look, you need to slow down. I mean just calm down.' And then he just got right in my face as if he wanted to just beat me up," he said. "I said, 'Stop being a such and such and calm down and get back into the game.' And he just got even closer and closer, and I just said, 'That's it, you're sacked.' I said, 'I will never have you caddie ever again.' And we never spoke for the rest of the (first nine), and when we got to 18 we walked off, and he said some smartass remark to me, and I said, 'You don't deserve to be caddying out there.' And he just got right in my face and threatened me, so I said, 'Go.' So he left."

While Middlemo confirmed most of Allenby's remarks, he disputed the initial conversation that led to the dispute.

"I just wished it had never gone this far. But he is again using the media to make himself look like the victim," Middlemo told ESPN.com.

"The discussion was only about waiting for the wind to die down and hit the 8-iron; the 7-iron was never discussed. Not once. He came up 10 meters short of the front of the green. ... He hit a bad shot.

Robert Allenby withdrew from the Canadian Open after a 9-over 81 and a confrontation with his caddie. Mike Ehrmann/Getty Images

"He said, 'I can't believe this fat c--t,' loud enough for everyone to hear. There's a lot as a caddie I can take but a personal attack like that. ... If this was an office in any country in the world, that would be considered bullying. ... I can take it if you call me the worst caddie in the world, tell me I'm horrible at picking clubs, but there's a line you just can't cross."

Middlemo told GolfChannel.com that it was Allenby who lost his cool and became verbally abusive.

"I said, 'Look, if you want someone to abuse, get someone out of the parking lot,'" Middlemo said. "He said, 'I'm going to get a caddie banned for life on this tour.' And I asked if it was me, and he said, 'Yes.' That was it."

Middlemo is the fourth caddie to walk off during a round while working for Allenby.

After Middlemo walked off the course, Allenby carried his own bag to the 18th green to speak with officials, and according to Golf.com, that's when a fan offered his services.

Allenby said yes to the fan, Tom Fraser, a 61-year-old local school principal, allowing him to caddie for the last nine holes. Allenby birded the first hole with Fraser on the bag but later had four straight bogeys, finishing with a 43.

Allenby withdrew from the tournament, finishing at 9 over.

"He did a great job," Allenby said of Fraser, according to ScoreGolf.com. "He did everything he was told. He was a nice guy. I'm really thankful that he helped me out. It was nice to have someone friendly on the bag who didn't want to threaten me."

A source who was walking with the group verified Middlemo's version to ESPN.com.

PGA Tour official Steve Cartman has spoken to multiple parties who witnessed the events.

Earlier this year, Allenby was involved in a strange off-course incident in Hawaii. In January, after missing the cut at the Sony Open, Allenby said he was robbed and beaten and needed help from a homeless woman.

"You think ... that happens in the movie, not real life," Allenby told The Associated Press at the time. "I'm just happy to be alive."

Allenby posted a photo on his Facebook account showing a facial injury that he said came from being thrown in the trunk of a car.

"I don't know what they hit me with between the eyeballs, whether a fist or a baseball bat," he said then. "Whatever it was, it hurts."

Allenby returned to play later in January, saying he had "no memory" of what happened for over two hours that night in Hawaii.

Allenby has missed the cut nine times and now withdrawn twice since that incident.

ESPN.com's Michael Collins contributed to this report.