Chara, the NHL's tallest player ever at 6-foot-9, was flipped head over heels into the Capitals' bench on a shove from the 6-3 Ovechkin late in the first period.
The TD Garden crowd gasped, but play continued and there was no immediate on-ice retaliation. The Bruins captain tumbled back onto the ice quickly and rejoined the play.
The 41-year-old Chara has made a name for himself delivering bruising hits.
Ovechkin scored his NHL-leading 31st and 32nd goals, and Nicklas Backstrom got the winner in the third period to lift Washington over Boston 4-3.