Rasmus Dahlin put Buffalo ahead 2-1 at 7:25 when Peyton Krebs sent a pass from behind the net to the defenseman in front.
"I thought we had good momentum going into the second," Batherson said. "And there was just power play, penalty kill, power play, penalty kill, didn't have much 5-on-5 and sometimes that affects the legs."
Olofsson made it 3-1 with 42 seconds remaining in the third period, then scored again with 27 seconds left for the 4-1 final.
"Execution," Smith said. "I think the guys wanted it too much probably and just were squeezing maybe. Didn't go in the net. But there was plenty of chances there, just doesn't go in."
NOTES: Alex DeBrincat had seven shots on goal in 19:06 of ice time, and Claude Giroux had two shots on goal in 17:54 in each forward's regular-season debut with the Senators. Ottawa acquired DeBrincat in a trade from the Chicago Blackhawks on July 7. Giroux signed a three-year, $19.5 million contract ($6.5 million average annual value) on July 13. … Sanderson played 22:21 and had one shot goal in his NHL regular-season debut. … Sabres defenseman Mattias Samuelsson, who signed a seven-year, $30 million contract ($4.29 AAV) on Wednesday, had one shot on goal and four blocked shots in 19:16. … Each team was 0-for-4 on the power play. … Prior to the game, the Sabres and Senators came together at center ice for a moment of silence to honored the victims of the May 14 mass shooting at a Buffalo supermarket.