Jon Lester left Joe Panik Jersey his start against the Brewers on Monday with lower back tightne s.The 34-year-old left hander allowed three runs and eight hitsin 5 2/3 innings on the mound before exiting with the injury. He also struck out sevenMilwaukee hitters.Jon Lester exited tonight’s game due to low back tightne s. Chicago Cubs (@Cubs) September 11, 2018Lester was replaced in the game by Carl Edwards Jr., who recorded the final out Willie Mays Jersey of the sixth.Lester, a five-time All-Star, came into the start with a 15-5 record and a 3.53 ERA this season. He had struck out 126 and walked 56.The Cubs entered play Monday with an 83-59 record. They led Milwaukee by two games for first place in the National League Central.The Brewers were 2 1/2games ahead of the Cardinals for the first NL wild-card spot.