John Lackey picked up right where he left off before suffering his injury scare in Toronto. The Red Sox starter allowed one run on five hits over six innings, leading his team to a 6-1 win over the Astros Sunday at Fenway Park. Lackey’s ERA after two starts stands at 2.61, having given up two runs over 4 1/3 innings against the Blue Jays before leaving with a strained right biceps. With the victory — the Red Sox’ 18th of the season (18-7) — the Sox have now matched their total number of series sweeps for the entire 2012 campaign (3). The game ended on a diving catch by Daniel Nava in which the right fielder extended his entire body in hauling in Robbie Grossman’s deep flay ball.