A video posted on YouTube shows a Toronto Maple Leafs fan laying on the ground and not moving. [videoembed id=145794]
The victim told TheLeafsNation.com, a Maple Leafs sports blog, that he was blindsided with a punch to the head. The victim's friend told the blog that he didn't see the punch happen, but that he guessed it was a "pissed off fan."
Boston police did not immediately respond to a request for information.
The Bruins suffered a 4-2 loss against the Leafs Saturday that evened the first round playoff series at one game each. The Bruins play Game 3 against Toronto in Canada Monday night. It will be Toronto's first home playoff game in nearly a decade.
Follow Michael Naughton on Twitter @metrobosmike.