The Miami Heat forced a deciding match in the Eastern Conference finals with a 98-79 victory over the Celtics on Thursday in Boston.
LeBron James exploded with 45 points and 15 rebounds, shooting 19 of 26 from the field, in 45 minutes of action.
Dwyane Wade scored 17 points for the Heat, who won Games One and Two of the series before dropping the next three.
Oklahoma City also fell two games behind in the Western Conference finals but won four straight to secure a place in the NBA Finals.
Boston was led by Rajon Rondo, who had 21 points and 10 assists, while Kevin Garnett and Brandon Bass had 12 points apiece. Paul Pierce chipped in with nine.