Howard tried to clear the puck from behind his net, but it hit Buffalo's Brian Flynn and popped over the net to set up Girgensons' backhander that pulled the Sabres within a goal.
"It was unfortunate that it hit him and ended right on the guy's stick," Howard said. "My bad."
Howard made 19 saves, playing an Atlantic Division game against the young Sabres.
Buffalo had a two-man power play for 1:31 early in the first period and for 51 seconds late in the second, but couldn't take advantage. In between those 5-on-3 opportunities, the Sabres were scoreless on three power plays.
"It could've been a difference-maker for our team, and it wasn't," Buffalo forward Steve Ott said.
Ryan Miller gave up goals on the fifth and sixth shots he faced and finished with 32 saves. He didn't seem to have much of a chance on either goal.
Samuelsson swiped the puck out of the air and into the net off a centering pass from Cory Emmerton 12:05 into the game.
"It was pretty," Miller said. "You'd think it was prettier if it didn't happen to you."
Datsyuk got a giveaway in the Sabres end, skated between the circles and backhanded a shot that Miller appeared to not see until it was too late at 12:41 of the first.
"We made a second mistake up the wall and we turned it over to a real good player," said coach Ron Rolston, following his first game behind Buffalo's bench.
The Red Wings didn't create a lot of chances the rest of the game, but did have a goal waved off because Daniel Cleary was called for interference against Miller.
"We hung around long enough and got one, so we were still in it at the end," Rolston said. "But obviously our power play didn't help us."
Detroit is hoping to start strong this season and finish better than it has the previous four years when it failed to get past the second round of the playoffs. The Red Wings seem to have a deep roster including a pair of veteran newcomers, Daniel Alfredsson and Stephen Weiss.
Buffalo, meanwhile, is rebuilding.
The Sabres played three teenagers: Girgensons, Mikhail Grigorenko and Rasmus Ristolainen. Buffalo selected Ristolainen, an 18-year-old defenseman from Finland, with the No. 8 pick in this year's draft. Grigorenko, who had five points in 25 games last season, and Girgensons were chosen in the first round last year.
"This is a good experience for them, playing a team like that with the speed that they have," Rolston said.
Samuelsson played in just four games last season because of injuries and didn't have a goal. ... The Sabres played more than two teenagers for the first time since the 1995-96 season, when they had five on their roster. ... The Red Wings are 9-1-1 in their last 11 games against Buffalo, a team they will play four times this season.
Copyright by STATS LLC and The Associated Press
DETROIT, MI - OCTOBER 02: Jimmy Howard #15 of the Detroit Red Wings is introduced during the home opener prior to...