Alfredsson was held without a point by his former team. The Swedish winger spent 17 seasons with the Senators before signing a one-year deal with the Red Wings in the off-season.
Craig Anderson made 31 saves for Ottawa.
Todd Bertuzzi scored for the Red Wings.
Spezza has seven goals on the season, trailing only Washington's Alex Ovechkin, who leads the NHL with nine. Ryan has scored six.
Alfredsson is Ottawa's career leader in games (1,178), goals (426), assists (682) and points (1,108), but he had a quiet game Wednesday, along with the rest of the Red Wings. Alfredsson had two shots and was called for a third-period tripping minor.
BRUINS 5, SABRES 2
Dougie Hamilton also scored for Boston. The Bruins are 6-2 overall and have won their first four road games for the first time since 2010.
By the time Krug netted the second of his two third-period goals, the fans launched into what have become regular "Fire Darcy! Fire Darcy!" chants in reference to Sabres general manager Darcy Regier.