CINCINNATI -- Reds right fielder Nick Castellanos knew exactly what he wanted to do.

In the bottom of the ninth inning vs. Nationals reliever Patrick Murphy on Saturday, Castellanos slugged a home run to center field to give Cincinnati a 7-6 walk-off victory at Great American Ball Park.

“I was looking to hit a home run. I’m not going to beat around the bush there,” Castellanos said. “I knew [Murphy] threw really hard, so any time a pitcher is proud of their fastball and wants to play fire with fire, I love that game.”

With one out, Castellanos missed Murphy’s opening salvo, a curveball, for strike one. On the next pitch, he drove a four-seam fastball for his 31st homer of the season -- extending his career high. It was also the second walk-off homer of his career and his second homer in the last two nights.

“It doesn’t surprise me,” Reds manager David Bell said. “He just continues to master his craft and he loves doing it. I could see that just because he was so focused on driving the ball and hitting it as hard as he can. He knew to win the game right there that it was going to take a home run. But I think he stayed within himself to do that. I think he knows what that means.”

The Reds (80-75) remain six games back of the scorching-hot Cardinals for the second National League Wild Card spot with seven games remaining. The elimination number for the Reds is two, meaning any combination of St. Louis wins or Cincinnati losses reaching that mark would end the bid for the postseason. The Cards have won a team-record 15 straight games.

Even with the postseason odds stacked against them, the Reds continued to fight to the end in back-to-back games with the Nationals. For the second night in a row, it was a walk-off winner after an 8-7 win in 11 innings Friday.

“That’s all we can do,” Castellanos said. “Everybody is extremely aware of what’s going on, obviously the stretch the Cardinals are on is very impressive. The only thing we can do is control what we can control. That saying probably gets kind of repetitive and worn out. But everything seems to always come back to that.”

Reds starter Vladimir Gutierrez lasted only 2 2/3 innings, forcing Bell to patch together the night with eight pitchers after he used nine to get Friday’s win.

The two teams exchanged early leads a couple of times. Cincinnati was trailing, 5-3, in the bottom of the fifth inning before it scored two runs to tie it up. Following Max Schrock’s sacrifice fly, Castellanos hit a check-swing blooper into right field for the game-tying RBI single.

After the Reds had the bases loaded with one out in the sixth inning and didn’t cash in, reliever Jeff Hoffman surrendered a solo homer to Keibert Ruiz in the top of the seventh that put Washington back up by one run. The Reds tied the game again in the bottom of the seventh when Kyle Farmer hit a one-out RBI double through the gap in left-center field that scored Castellanos, who led off the inning with a walk.

“You have a choice to make, really, every day, and our team continues to make the right choice,” Bell said. “That's to go out and give everything you have. There's really no other way to play this game, if you don't -- you get beat, even embarrassed, because it's so hard. They're going out and they care tremendously about one another. Our players continue to enjoy playing with each other, and I think these wins are rewarding for that. It'll help us just continue it and finish strong.”

One of those players trying to end on a high note is Castellanos, who is batting .310 with a .930 OPS and 91 RBIs in 132 games this season. This could be his final homestand with the club if he exercises an opt-out clause in the four-year, $64 million contract he signed ahead of the 2020 season.

“First, I'd say the city of Cincinnati recognizes talented players, guys that compete and play hard and play to win,” Bell said. “And it's pretty obvious, Nick doesn't talk a lot about that, but just watching him play, it's pretty obvious how he plays the game. He definitely plays it with passion. He's a great player. Nick, I also believe that it's very important to him. It shows. It's been a great connection. It's great to see players appreciate it.”