Luis Castillo didn't get to finish September undefeated, but the Reds starting pitcher knew on Saturday after a 7-3 loss to the Twins that more important matters lie ahead.

Castillo completed 77 pitches over four innings while allowing four earned runs -- equaling his previous total for the month -- on six hits, with four strikeouts. His next assignment will be starting Game 2 of the National League Wild Card Series on Thursday.

• Box score

“It’s my first time in my Major League career that I will be going to the playoffs and pitching in the playoffs," Castillo said via translator Jorge Merlos. "I’m really happy that I’m going to go out there.”

Castillo was 4-0 with a 1.26 ERA in his last four starts, but he was unable to become the first Reds pitcher with five September wins since Johnny Cueto in 2014.

"I thought his stuff was pretty good. The slider wasn’t as good," said catcher Curt Casali, who caught Castillo's previous four outings. "We just didn’t execute a lot. I think the big takeaway from tonight was I just called horrible pitches. The Twins were just three steps ahead of me all night. That’s what happens. Luis relies on me a lot; I take great pride in that. I didn’t do him any favors tonight."

The Reds had a team celebration Friday night after clinching their first playoff berth since 2013 and put it behind them by Saturday afternoon. 

"New territory for me. New territory for most of the guys on the team," Casali said. "How do you respond after you have a great night like last night? For the most part, I thought we played pretty well tonight."

Cincinnati came out swinging, taking a 2-0 lead in the top of the first inning against Michael Pineda when Joey Votto hit an RBI double to left-center field and Mike Moustakas' sacrifice fly brought home Jesse Winker.

Amid a rainy night at Target Field, Castillo was unable to hold onto the lead. The Twins notched two hits in the first inning, including Nelson Cruz's two-out RBI single. They then took the lead with three consecutive one-out doubles for two runs in the third. The fifth double of the game against Castillo was hit by Marwin Gonzalez with one out in the fourth. Gonzalez later scored from third base on a wild pitch.

"I don't know if it was the rain ... he's just been so good recently that it wasn't as sharp tonight," Reds manager David Bell said. "Good hitting team, but you know, we know, when he's on, it doesn't really matter who he is facing, he can dominate. And tonight just wasn't one of those nights. He kept us in the game, and he was still good. But he definitely got his work in, and he'll be ready to go next week."

Anthony DeSclafani, who will pitch out of the bullpen in the postseason after being in the rotation, gave up three earned runs on four hits over three innings in relief. 

Saturday’s loss was only Cincinnati’s third in its last 13 games. The good news for the 30-29 Reds was it didn't cost them in the postseason seedings. Because the No. 8 seed Giants lost, Cincinnati held onto the No. 7 seed, and there is still a chance to move up after the Cardinals (29-28) also lost to keep the teams relatively even in the National League Central.

"I think we still understand the importance of these games," Bell said. "We definitely competed. Both teams still have something to play for, and it's better like that. We need to keep playing that way, tomorrow as well. It can affect a lot, so we'll come back out and play hard and do everything we can to get a win tomorrow and see how it all shakes out."

The first of the four straight series the Reds won to ignite their late hot streak came on Sept. 11-13, when they took two of three games at St. Louis. Castillo opened that series with the first complete game of his career.

"That was pretty incredible," Casali said. "He did something he’s never done in his career, and everybody just took a second to appreciate that. On a team that was left for dead pretty much, he’s still going out there and doing that for us, throwing a complete game. I think everybody just kind of jumped on board after that. … Taking two out of three against the Cardinals that weekend was kind of the start of it. Man, just an absolute roll through the last couple of weeks."