With a little more than a week to go until opening night on Oct. 5, the Bruins lineup is slowly coming into focus. Rookie right winger Anders Bjork, both a good fit with Patrice Bergeron and Brad Marchand and strong on the puck in his own right, is a smart bet to start the season on the top line. Fellow rookie Jake DeBrusk might not be as firm as the left winger for the David Krejci-David Pastrnak unit, but another good showing in one of the last two preseason games might get him the job. Riley Nash and Noel Acciari appear to be a solid fourth-line combination that is just waiting for a left winger to trickle down to them. But the third line remains a conundrum, with David Backes the only clear piece, most likely at right winger. The battle for the centerman spot appears to be a three-man race, with the larger, more physical Sean Kuraly pitted against the smaller, speedier Austin Czarnik and the beefed-up Ryan Spooner. Kuraly was on the ice for both Chicago goals in Monday’s 4-2 Bruins preseason win while Spooner had a good night against the Blackhawks. Czarnik, meanwhile, has had an excellent camp. When Spooner was left out of the lineup for games in the playoff series against the Ottawa Senators last April, it seemed like his time had run out, even if the B’s signed him to a one-year deal for $2.825 million, maintaining the rights to an asset. But Spooner has had a decent camp and, in Monday’s win, he used his added 10 pounds of muscle to knock Tanner Kero off the puck at the defensive blue line to start the transition that led to Pastnak’s goal. Spooner also made a nice lob pass that sprung Pastrnak for a breakaway.