Lightning center Tyler Johnson said his pass on Tuesday's first-period power play was definitely a hard one.But Johnson had faith rookie defenseman Mikhail Sergachev, 19, could handle it while sliding to the top of the left circle."He has of the best, if not the best, shot on our team from there," Johnson said.That's high praise, especially on a team that includes star snipers like Nikita Kucherov and Steven Stamkos. But Sergachev cashed in, ripping a one-timer past Buffalo goalie Robin Lehner to give the Lightning the lead for good in a 2-0 victory.Of Sergachev's six goals this season, four were game-winners. Only three other rookie defensemen in NHL history have scored more than four game-winners in a season. Dion Phaneuf (7 in 2005-06), Gord Fraser (5 in 1926-27) and Shayne Gostisbehere (5 in 2015-16) are the others."He's got tremendous offensive instincts, an unbelievable shot," said defenseman Victor Hedman said of Sergachev. "To see him get rewarded is always fun. He's earning his breaks too. He's been working hard in practice every day since camp started. How many goals does he have now? Six? He's running away with it."Sergachev said the fact his coaches trust him gives him confidence, and they've put him in good positions to succeed. Coach Jon Cooper has managed Sergachev's minutes and matchups, pairing him with veteran Anton Stralman, while also using his strengths on the second power play unit."With his young age, to have those offensive gifts that he has, he's got a high ceiling," coach Jon Cooper said. "You put the puck in his wheelhouse and he can shoot it, and that's what he did."ON THE BOARDVeteran defenseman Dan Girardi joked to Hedman before Tuesday's game that it would be a good night to get his first goal with Tampa Bay.With Girardi growing up about an hour and a half away in Welland, Ontario, he had between 20 and 25 friends and family in the stands at KeyBank Arena.Girardi's prediction was prescient, as he scored on a shot from the point in the second period, his shot deflecting off a Sabres defenseman. His teammates collected the puck as a memento. "He's just a great team guy, a phenomenal guy – it was huge to see him get it," Hedman said.NUTS AND BOLTS*With no morning skate Wednesday, we won't know the lineups until tonight. But it wouldn't be surprising to see goalie Andrei Vasilevskiy back in net. Vasilevskiy picked up his NHL-high 16th win Tuesday. The Lightning doesn't play again until Saturday, and Vasilevskiy's previous start was Friday, so three games in eight days isn't too much.*D Slater Koekkoek delivered another solid performance Tuesday, playing in his third straight game. Would be nice to see Koekkoek get a string of a half dozen or more games, as you can see his confidence is growing. But am expecting Koekkoek to be out tonight, with the Lightning going 12/6 with J.T. Brown back and Andrej Sustr back.*The Lightning, which arrived at 1 a.m. from Buffalo, got a rude wakeup call at 9 a.m. today when the emergency alarm went off at their team hotel in Boston. A couple firetrucks came, but it turned into a false alarm, which was triggered in the parking garage.*The Bruins have been banged-up, but could get two of its stars back tonight with Brad Marchand and David Backes game-time decisions.