By Zuri Berry, Boston.com Staff

TAMPA -- Teddy Purcell poured in two goals, Martin St. Louis added two more, and despite a hat trick from David Krejci, the Tampa Bay Lightning held on to beat the Bruins, 5-4, Wednesday night to force a Game 7 in the Eastern Conference finals.

The Bruins will host the Lightning at 8 p.m. Friday to decide which team gets to face the Vancouver Canucks in the Stanley Cup Final.

It was the third time Bruins goalie Tim Thomas had allowed five goals in the series.

The Lightning got off to a strong start with a goal 34 seconds into the first period. Vincent Lecavlier won a faceoff in the Bolts' offensive zone, which he bounced back to Purcell for a one-timer to get Tampa on the board.

Milan Lucic, who had been scoreless in this series against the Lightning, tied the game after beating goalie Dwayne Roloson on the glove side 7:09 into the first.

Krejci followed with a goal after a Steven Stamkos turnover that led to a two-on-one break.

The Lightning's St. Louis knotted the game 7:55 into the second period on a power-play goal after Dennis Seidenberg was whistled for cross-checking.

Purcell scored the go-ahead goal in the second period, on another power-play strike. This time, he got a little help on his slapper from the traffic in front of Thomas as the puck banged its way into the net.

The Lightning didn't relent in the third period with Stamkos scoring 34 seconds into the final period on a one-timer from the left circle.

Krejci brought the Bruins within one -- twice. He scored his second goal of the game on a power-play 9:46 into the final period. Nathan Horton dished to Krejci for him to beat Roloson. St. Louis extended the Lightning's lead back to two goals less than 30 seconds later, scoring on a two-on-one after the Bruins' Johnny Boychuk was caught out of position. But then Krejci was fortunate enough to be in position as Roloson lost his stick before his shot went off Lightning forward Dominic Moore and into the net.

With more than six minutes left in the game, the Bruins couldn't find the equalizer despite numerous chances. They went to an empty net with little more than a minute remaining.