Holtby tied a season high with 38 saves, Jay Beagle and Nicklas Backstrom scored second-period goals, and Washington extended its point streak to nine games with a 2-1 victory on Monday night.
"There's no way we win that hockey game if Braden doesn't give us the performance he did in the first," Trotz said of Holtby, who made sparkling saves during two Ottawa power and stopped 14 shots overall in the opening period.
Washington has won three in a row and is 7-0-2 in its past nine games. Holtby has been in net for all of them.
"It's no surprise to the guys in the room here," Beagle said of Holtby. "He is playing great and we're kind of getting on his shoulders a little bit."
Washington moved ahead of the New York Rangers and into third place in the Metropolitan Division. Those teams will meet Tuesday night in New York.
Backstrom broke a 1-1 tie with 35 seconds left in the second period during a power play. He has 11 goals this season, including six in his last five games. Beagle made it 1-0 at 13:59.
Mike Green assisted on both Capitals goals as Washington snapped a seven-game losing streak against Ottawa.
Erik Condra scored his third goal of the season to tie it 1-1 in the second period, and Craig Anderson stopped 21 shots for Ottawa. The Senators are 3-3-1 since Dave Cameron replaced Paul MacLean as head coach.
"I thought we were pretty solid," Cameron said. "You're going to win most of those games if you play that well."
Ottawa pulled Anderson with 1:58 left, but couldn't get the equalizer past Holtby.
"That's something we've struggled with in the past.and I think we've done a great job of getting better at that," Holtby said of defending the lead. "They put up a lot of shots in the third period, but not a whole bunch of quality chances."
Beagle opened the scoring after he snared a long pass from Evgeny Kuznetsov. Despite having Ottawa's Jared Cowen draped over him, Beagle managed to fire a shot that deflected in off Anderson's left pad for his fifth of the season.
The Senators tied it less than two minutes later when Condra stripped the puck from Green at the Capitals blue line, skated in alone and scored.
Alex Ovechkin then drew a holding penalty on Eric Gryba at 18:08, and Backstrom's high wrist shot from the right circle beat Anderson.
Washington was outshot 14-6 in the first period despite three power plays, including a 5-on-3 advantage for 1:06.
"We had a 5 on 3, and we really didn't get anything," Trotz said. "I was thinking, `OK, our goaltender is standing on his head and we (don't) score on a 5 on 3, the odds of winning this game are drastically reduced.'"
Ottawa's power play also failed in the period, largely because of Holtby.
With the Capitals down a man, he grabbed Clarke MacArthur's one-timer against the post at 4:32. The save stood up to a video review that confirmed he didn't catch the puck over the goal line.
Minutes later, with the Senators on another power play, Holtby made a pad save against Kyle Turris off a point-blank rebound try.
"We all had a few good chances," MacArthur said, "just nothing is going in."
NOTES: Washington recalled C Andre Burakovsky and LW Aaron Volpatti from Hershey of the AHL. Volpatti (upper body) will return to the team's injured, non-roster list and long-term injury list. ... The Capitals will begin a three-game trip on Tuesday and then return home to play the Chicago Blackhawks in the Winter Classic on New Year's Day. ... The Senators are off until Saturday when they host the Detroit Red Wings.