Sabres fail to rally past Capitals
It was Bradley's first multiple-point game since Jan. 7. Nicklas Backstrom and David Steckel also scored as the Capitals took a 3-0 lead early in the second period.
Washington, which has a league-high 29 points, is 10-1-0 at the Verizon Center.
Alexander Semin had an empty-net goal in the final seconds and an assist to extend his point-scoring streak to nine games, the longest by a Capital this season.
Michal Neuvirth made 31 saves for his 12th victory of the season.
Two Buffalo penalties within 13 seconds gave the Capitals a 5-on-3 chance midway through the first period, and Washington took advantage.
Semin found Backstrom with a cross-ice pass through the crease, and Backstrom hammered it home from the right side of the net for his sixth goal of the season at 12:31.
Washington made it 2-0 a few minutes later on Bradley's second goal of the season.
Jason Chimera made a between-the-legs pass from behind the net and facing the boards, finding Bradley in front of the net. Bradley's shot trickled through goaltender Ryan Miller's pads to extend the lead.
Another Chimera pass from behind the net - this time facing the play - led to the Capitals' third goal, as he found Steckel in front of the net at 2:45 of the second period.
Roy put the Sabres on the board with a power-play goal at 12:07, and 48 seconds later Leopold put in a loose puck to make the score 3-2.
Rob Niedermayer tried to pass to Cody McCormick in the left circle, but Capitals defenseman Jeff Schultz contested the pass. As the two players were tied up with the puck sitting behind them, Leopold skated in for the shot.