Lester pitched well in Game 1 of the NL Division Series against the Cardinals, fanning nine in 7 1/3 while yielding three runs, although it was in a losing effort. He lobbied to start Tuesday's Game 4 of the NLDS, and he would have been the starter if the NLDS went to a fifth game.
Arrieta's command was a bit off during his start in Game 3 on Monday, as he allowed four runs over 5 2/3 innings. He has also carried a heavy workload recently, so the Cubs want to be careful that he does not get fatigued.