SUNRISE, Fla. -- Sam Reinhart scored 17 seconds into overtime to cap a late scoring flurry and give the Florida Panthers a 4-3 victory over the NHL-leading Boston Bruins on Saturday night.

The result, coupled with a 3-2 defeat to Tampa Bay on Thursday, gave Boston its first two-game losing streak of the season.

"We're facing a little adversity right now," Boston coach Jim Montgomery said on his postgame interview on NESN. "First time all year that we haven't prevailed in two games in a row. So, we're going to have look at what we're doing wrong, and ways to get better."

After David Pastrnak scored to give the Bruins the lead with 48.6 seconds left in regulation, Florida captain Aleksander Barkov tied it with 2.4 seconds remaining.

The Panthers, the NHL Presidents' Trophy winners last season, won for the first time this season when trailing going into the third period. Florida had been 0-17-1 in such situations while the Bruins were 26-0-1 when leading after the first 40 minutes.

Craig Smith and Charlie Coyle also scored for Boston, and Jeremy Swayman made 34 saves in the loss. The Bruins had won six in a row before their road trip to Florida.

"For me, it's the third period," Montgomery said of both losses this week. "Both teams pushed hard, and I don't think we matched that intensity."

The Panthers received goals from Brandon Montour and Sam Bennett. Alex Lyon, Florida's usual starter for its AHL team in Charlotte, stopped 36 shots, playing for the second time in as many nights.

"I just think we've been due for a game like this, and to earn an outcome like this," Florida coach Paul Maurice said. "We just kept getting kicked in the teeth in that game, and we wouldn't quit."

Coyle was credited with the goal that gave Boston a 2-1 lead late in the second period after Bennett swatted the puck out of the air and scored into his own net.

"We know everyone's going to come gunning for us, and ready to play, whether they're on a back to back, or whatever the case is," Coyle said. "It is up to us, to bring that focus and be prepared for it."

Bennett did redeem himself at 8:29 of the third, tying it with a big wrist shot from the right circle. He was able to fool Swayman a bit as he looked to pass the puck, but instead wound up and let one go from 20 feet out.

Lyon, making his fifth consecutive start in place of the injured Sergei Bobrovsky, lost to the Los Angeles Kings 4-3 on Friday night.

According to ESPN Stats & Information research, this was the first time in franchise history where the Bruins lost when scoring a go-ahead goal in the final minute of the third period.

The Associated Press contributed to this report.