The Kings and the St. Louis Blues played an eventful first period Tuesday night at Staples Center. The Blues took a 2-1 lead on goals from Alex Pietrangelo and Vladimir Sobotka and skated as if on a mission. They also were willing to drop the gloves and engage the Kings, who swept them from the playoffs last spring. There were three fights in the first period, including a clear decision for the Kings’ Kyle Clifford over the Blues’ Roman Polak. Rookie defenseman Jake Muzzin scored the Kings’ lone goal in the opening period.