Mike Greig, a New Zealander living in the United States, was walking with a friend at lunchtime on the day of the Rugby Championship test against Argentina at La Plata when two men on a motorbike attacked them.
"A motorbike rode up and the driver king hit me across the side of the head with a helmet," he said. "My buddy was attacked by the driver's colleague.
"I went down and then had a scrap with the guy before he turned on my mate. After a scuffle they took off. Luckily they got nothing. I am pretty sure he knocked me unconscious as I can't recall much at all."
A hospital visit today confirmed a fractured jaw and he will see a surgeon tomorrow. "Seems like I will be using a straw [to eat] for a while," he said.
The attack on Mr Greig, who was wearing an All Black hat when set upon, follows last year's assault on All Black chairman Mike Eagle and director Gerard van Tilborg by two men who stole Mr van Tilborg's Rolex watch.
That incident, a day after the All Black test at La Plata, also occurred near the team's hotel in Buenos Aires, which is known as a relatively safe area.
Several New Zealand supporters were also targeted by opportunists last year and TVNZ reporter Steve Marshall had his camera stolen.
Undeterred by the experience and his painful injury, Mr Greig went to the test where he hosted business colleagues, but said he had learned a valuable lesson.
"Most people are great down here - [it's] a pity that the street criminals prey on tourists. Next time I will stick to busier streets and be more aware."
Mr Greig said the incident didn't spoil his enjoyment of the game, which the All Blacks won 33-15.
"The ABs looked good in the second half. I enjoyed the way the locals respect the haka."
