"It was pretty lucky there. I didn't see it right away, and then it was more reflex than anything," Grossmann said.
Part of the puck appeared to cross the goal line. After a lengthy video review, the no-goal call on the ice was upheld.
"I was pretty sure it was out, but then when you wait that long, you never know," Grossmann said. "I think they made the right call."
After the review, the Senators went flat and the Flyers seemed to be revived.
Kimmo Timonen (three points) and Wayne Simmonds scored 23 seconds apart as the Flyers snapped a 2-2 tie and took a 4-2 lead with 8 minutes, 7 seconds remaining.
Adam Hall later added an empty-net goal.
"We haven't been a good hockey club at home," said Mason, whose team is now 4-7 at the Wells Fargo Center. "We've had leads going into the third and let them go and lost a lot of valuable points. So to continue the stronger play we had on the road is nice to see."
The Flyers, who started a three-game homestand, are on a 4-0-1 run, lifting their record to 8-10-2. They are 8-7-2 since coach Craig Berube replaced Peter Laviolette.
The Senators had tied it at 2-2 as Turris scored on a rebound, backhanding the puck into the net on a power play with 16:48 left in the third period.
The Flyers' mostly anemic power play has produced more boos than goals at home games this season. Before Claude Giroux scored late in the first period, they were 3 for 41 (7.3 percent) on the power play at the Wells Fargo Center, placing them next-to-last in the NHL at home.
After taking a slick right-circle pass from Jake Voracek, Giroux's left-circle shot went past sprawling goalie Robin Lehner with 2:16 left in the opening period to give the Flyers a 1-0 lead.
A little over five minutes into the second period, the Flyers got a gift and made it 2-0 on Sean Couturier's first goal of the season. Couturier, who missed a wide-open net on a first-period rebound, shot the puck from behind the goal line near the boards and somehow beat Lehner to the short side.
"It felt good to finally get one," Couturier said. "I got a lucky bounce and I'll take it."
Ottawa took advantage of Brayden Schenn's tripping penalty to get within 2-1. Clarke MacArthur scored from the left circle with 11:47 left in the second. Luke Schenn (five hits) and Zac Rinaldo appeared to screen Mason, who blanked the Senators, 5-0, last week.
Mason made one of his best saves of the season with 31.2 seconds left in the second period, stopping MacArthur on a one-timer from the doorstep. Mason, showing great instincts, slid to his left and got his left pad on it. Bobby Ryan, the pride of Cherry Hill, made a spin-around, one-handed pass to get the puck to MacArthur.
With 5:06 left in the game, Mason stopped Turris on a penalty shot after the Senators center had been pulled down by Timonen on a breakaway.
"Early in the season, guys were really struggling to find their games," Mason said. "You can see now guys are starting to play with a lot more confidence."
Grossmann sparks third-period surge as Flyers prevail.
FLYERS 5 | SENATORS 2