CHICAGO -- The Chicago Cubs lost 13-6 to the Cincinnati Reds on Monday. Here's a quick look at the game.

How it happened: Justin Grimm gave up a pair of two-run home runs in the sixth inning, not long after the Cubs scored four in the bottom of the fifth to take a 5-3 lead. Addison Russell's two-run double tied the game 3-3, then Kyle Schwarber and Kris Bryant hit infield singles to drive in two more. The Cubs took a 1-0 lead in the third inning when Dexter Fowler hit a ball into the basket in left field for his 15th home run. But the Reds tied it and then went ahead 3-1 in the fifth. Joe Maddon walked Joey Votto intentionally with men on first and second. This strategy backfired, as Brandon Phillips singled home two runs. It looked like the Cubs took command the next inning, but Eugenio Suarez and Adam Duvall took Grimm deep in the sixth, and the Reds never looked back. The winning hit was Duvall's first home run of the season. The Cubs blew up in the ninth, as Starlin Castro made two errors and James Russell got hit hard, which allowed the Reds to score six runs. Addison Russell homered in the bottom of the inning to finish the scoring.

What it means: The Cubs played like they partied all night and took a red-eye home from Los Angeles. It got worse as the game progressed. You have to chalk it up to remnants of the previous 24 hours, as there isn't a better explanation right now.

It's easier to come down on starter Kyle Hendricks than on Grimm, considering the latter has been good more often than not. Hendricks is a different story. He looked OK for several innings Monday before starting to get hit hard. He simply needs to last longer; five innings is about his max these days. His ERA is 4.15 as we head into the final full month of the season. That's not good enough in a National League pennant race. James Russell is becoming a question mark, though he didn't give up any earned runs. Still, the hard hit balls count, and he has had several appearances with similar outcomes.

Maddon made a few decisions worth second-guessing. His walk of Votto with first and second base occupied was unorthodox, but Votto has been the best hitter in the league in the second half. More puzzling was a double steal attempt with two outs and the tying run on base in the eighth. Bryant was thrown out at second base, which ended the threat before Castro had a chance at the plate.

Castro: He made three errors in total and now has four in two days. Everyone was happy he made an error Sunday night, as it preserved Jake Arrieta's no-hitter, but that won't be the case this time. Castro bobbled, dropped and threw away a ball, which helped the Reds to six unearned runs in the ninth inning.

September call-ups: The Cubs will have some new faces come Tuesday, when rosters can expand to up to 40 players for the rest of the season. Expect Javier Baez to join the team along with newcomer Austin Jackson. David Ross is expected back from family medical leave, and the Cubs should call up some arms as well. CJ Edwards will probably be one of them, but he has been on paternity leave.

What's next: Game 2 of the series takes place Tuesday night, when Dan Haren (8-9, 3.90) faces Anthony DeSclafani (7-10, 3.84).