As it turned out, the Blues’ unraveling Tuesday night was slow in developing. Two nights after Ottawa netted three goals in 2 minutes, 35 seconds and rallied for a shootout win, Boston came to Scottrade Center Thursday and potted two goals in a span of 2:08 in the third period and erased the Blues’ hard work against the Bruins. But a pair of heads-up plays helped the Blues prevail in a 3-2 overtime victory in front of a standing-room-only crowd of 18,671. Defenseman Alex Pietrangelo used his stick to stop Boston’s Jarome Iginla from filling an empty net with 3:09 left in OT, a goal that would have drawn the curtain. Oshie pulled it down himself with 1:31 left, knocking down a puck rimmed around the end boards and tucking it past Boston goalie Tuukka Rask for an unassisted game-winner. The victory was the 110th with the franchise for Blues coach Ken Hitchcock, tying Scotty Bowman for fourth on the team’s all-time win list. But more importantly it rewarded goalie Jaroslav Halak for a strong game and redeemed the Blues after they blew their third straight two-goal lead, all on home ice and the last two in the third period. “We don’t want to make a habit of this,” Oshie said. “We work hard to get the lead and we’ve got to hold it, especially in our home barn.” Oshie brought the barn to its feet just 1 1/2 minutes before the Blues would have went to their third straight shootout. He capitalized on a misplay by a pair of former Blues’ draft picks — David Warsofsky and Carl Soderberg. After Warsofsky backhanded the puck to Soderberg behind the Bruins’ net, Soderberg attempted to clear it back along the boards. Oshie plastered himself against the glass and stiffened up, blocking the rim shot. The puck lay loose and he pounced on it. “I saw it laying there and just kind of started jamming,” Oshie said. “It might have went under his arm. A lucky bounce, and will take the point for sure.” The Blues closed their season series against Boston with a 2-0 record, sending the Bruins to just their second loss in their last eight games.