After seven strong innings, Medlen came out for the eighth inning to face Junior Lake and then the top of the Cubs' order. Medlen struck out Lake but then gave up a single to Starlin Castro with one out. Scott Downs entered and faced right-handed pinch-hitter Donnie Murphy, who laced a single to left to put runners on first and second.
Anthony Rizzo followed with a 3-2 double down the left field line that plated Castro and tied the game at one. David Carpenter replaced Downs, and allowed a RBI single by Dioner Navarro and a sacrifice fly by Nate Schierholtz to break the the tie and give the Cubs a 3-1 lead.
Pedro Strop struck out the side in the top of the ninth to seal the win for Chicago, and to keep Atlanta's magic number at one.
The eighth-inning comeback wasted what was a strong outing by Medlen. He scattered six hits and the one run while walking two and striking out six in his 7.1 innings of work.
Atlanta's lone run came on a RBI single by Evan Gattis in the fourth inning.
Clinching today is still possible, but the Braves need Washington to lose for that to happen.
The Braves are back in action tomorrow afternoon at 2:20 p.m. ET.
Win Expectancy Chart