The rookie goalie replaced the injured Michal Neuvirth during Monday night's Southeast Division showdown against Tampa Bay and had 21 saves in a 2-1 shootout victory that extended Washington's winning streak to five games.
Alex Ovechkin assisted on Washington's only goal in regulation, then scored in the opening round of the shootout to ensure the Capitals, who've won seven of their past eight games, would leave town with sole possession of first place.
Neuvirth left after the first period. He suffered an eye injury when he was hit by a shot in the mask in the opening minutes, but remained in the game until the first intermission.
"Michal's fine," coach Bruce Boudreau said. "Some part of the metal around his mask went into his eye, and he couldn't get it out. But he got it out, and he was fine after that. He's going to be OK."
Holtby stopped 14 shots in the second period, including a nice save on Simon Gagne on a power play that Ovechkin said "kept us in the game."
"I think it's one of the tougher things to do," Holtby said of entering the game cold.
"But you have so much adrenalin -- especially at this level -- that when you get told you're going in that you usually feed off that and then just hope for the best, try and battle as hard as you can, and hopefully the pucks hit you."
Alexander Semin came up big for the Caps for the second straight night, scoring his 24th goal of the season to tie it 1-all with 5:32 remaining in the third period.
Sean Bergenheim scored Tampa Bay's goal on a first-period power play, redirecting a shot past Neuvirth. Three minutes into the third period, Lecavalier added a goal that was disallowed because the officials ruled Martin St. Louis made contact with Holtby before the shot.
The Lightning disagreed.
"I've looked at it about 15 times now with about 20 people in my office," Tampa Bay coach Guy Boucher said. "Our guy never touched the goalie. It was their player's stick, and it's not a goal, then it has to be a penalty. It was a major tripping. That's a goal and that's 2-0, and that's probably the game."
Semin scored the winning goal in Washington's 3-2 overtime victory at Florida on Sunday night. That carried the Capitals past the Lightning into first place in the Southeast Division.
The loss was a season high fourth straight for the Lightning, who've scored just five goals during the skid that's dropped them from second to fifth in the Eastern Conference. The Capitals increased their lead in the Southeast to two points.
Dwayne Roloson stopped 29 shots for Tampa Bay. The 41-year-old goalie was less than six minutes away from shutting out the Capitals for the third time this season when Semin, with Ovechkin and Dennis Wideman getting assists, scored from the left circle to make it 1-1.
Washington's winning streak is its longest since the Capitals won six straight from Oct. 30 to Nov. 11.
Capitals center Nicklas Backstrom left the game in the second period with a sore finger. Boudreau said Backstrom wanted to re-enter the game, but was held out as a precaution.
"He just fell on his hand the wrong way," Boudreau said. "If you've ever had a sore finger or something and get it hit the wrong way, it gets pretty tender."
Tampa Bay's Steven Stamkos leads the NHL with 41 goals, but has only had one in the past 12 games. ... Lightning D Randy Jones left the game with what the team said was a lower body injury and did not return.