Samsonov kept a clean goal after allowing the first score of the game to Panthers winger Jonathan Huberdeau, stopping 29 of 30 shots. T.J. Oshie, Trevor van Riemsdyk and Alex Ovechkin were among the goal scorers as the Capitals took a 2-1 series lead vs. the Presidents' Trophy-winning Panthers.
With Samsonov the backbone at even strength and short-handed, Washington's penalty kill improved to 9-for-9 against Florida, which ranked fifth on the power play this season at just under 25%. The Panthers also led the league in scoring at more than four goals per game.
Samsonov replaced Vitek Vanecek for the third period of Game 2 on Thursday and stopped all 17 shots he faced. Vanecek had allowed five goals on 19 shots in the first two periods of the 5-1 loss, which tied the first-round series 1-1.
Capitals winger Tom Wilson, who suffered a lower-body injury in Game 1, remained out for Game 3.
Samsonov and Vanecek split the goaltending duties during the regular season, each starting 39 games. Vanecek had the edge in goals-against average (2.67 to 3.02) and save percentage (.908 to .896), while Samsonov posted the better regular-season record (23-12-5 to 20-12-6).
The Associated Press contributed to this report.