The Boston Bruins are set to face off against the Buffalo Sabres on Sunday afternoon in Game 4. This is a must-win for the Bruins, as losing would make them be down 3-1 in the series. That would be a very big hole for the Bruins to try to get out of. After their 3-1 loss to the Sabres in Game 3, the Bruins are entering Game 4 with a different-looking lineup. Most notably, Lukas Reichel is getting back into the Bruins' lineup, while top prospect James Hagens will be a healthy scratch. This is undoubtedly a major opportunity for Reichel. The 22-year-old forward has not played a game for Boston since their April 12 contest against the Columbus Blue Jackets, so he will be looking to impress. If Reichel stands out in this Game 4 matchup against the Sabres, it would help his chances of sticking in the Bruins' lineup as the playoffs carry on. This would be big for Reichel, as the 23-year-old forward is still looking to cement himself as a regular in Boston's lineup. Reichel appeared in 10 regular-season games for the Bruins following being acquired by the Vancouver Canucks, where he had three points. This included him scoring a goal and recording an assist in his Bruins debut against the Winnipeg Jets on March 19. If Reichel can put together another multi-point game in a crucial Game 4 against the Sabres, it would be huge for a Bruins club looking to tie this series back up.