If the Reds aren't careful, they're going to run out of must-win games.

Each game in the remaining three weeks is huge for a club still on the outside of the postseason picture. Cincinnati's faltering offense put together little in support of starting pitcher Tyler Mahle during a 3-0 defeat to the Cubs on Tuesday at Wrigley Field. For the 18-24 Reds, it was the sixth loss in their past nine games.

• Box score

"These are all must-win games and when you lose, it kills you," said Mahle, who struck out 10 over a season-high seven innings, tying his career high. "All we can do is find out what we did wrong and move forward and look to tomorrow to come out and win."

Before this radically different 60-game season began, much was said about the consequences being magnified for every pitch and every play. That could not have been underscored more than in the bottom of the second inning.

On a 2-2 count to David Bote with two on and two outs, Mahle threw a high fastball. Bote went up to get it and hit a liner to right field.

“I was trying to go up and away. Actually, it ended up being up and in," said Mahle, who gave up three runs, four hits and one walk. "If you’re trying to go up and away and the ball runs in, it’s just not as good of a pitch as if you were trying to go in. But at the same time, not only did I miss, I wasn’t fully [committed] to that pitch. … Bad things always happen when you do that. So, I shook yes to an up and away fastball and he hit it."

That mistake was compounded by another, on the very same play. Already playing shallow because of a stiff 20 mph wind blowing in, right fielder Nick Castellanos misjudged the ball off the bat and got a late jump. Then he got turned around, and the ball landed for a two-run triple by Bote and a 2-0 Cubs lead.

"That was a big play in the game," Reds manager David Bell said. "That's a tough play for an outfielder. It was a hard-hit ball, line drive right at the outfielder. It was really kind of tailing away from him.

"It's nearly impossible to get a ball out of the ballpark here when it's blowing in like that. I do think that was a factor, but just a tough play. Really hard-hit ball right at him, and you make one wrong reaction, and before you know it the ball is over your head, so that's what happened on that play."

Two batters after Kris Bryant was hit by a pitch on the left elbow in the third inning, Javier Báez muscled an RBI triple to the right-field corner.

Mahle has a 3.48 ERA over his past three starts -- two that went seven innings and the other was 6 2/3.

"Just really impressive," Bell said. "He showed last year and really, the last three starts, that he just continues to get stronger during the game. He's a big strong guy. He just keeps getting better and has the ability to go deep into games. I don't know that I've ever really seen a starter that really consistently just gets stronger as the game goes on like he does."

The Reds put together only five hits in the game as they were shut out for the sixth time this season.

Going into Tuesday, the Reds were only 2 1/2 games out of the playoffs, despite letting a potential four-game series win get away from them and settling for a split in Pittsburgh over the weekend.

On Wednesday comes the next must-win game. There are only 18 left on the schedule.

"Yeah, we continue to play. We continue to compete," Bell said. "This team cares tremendously about going out and doing everything we can to win. And that's all we can do. They're all must-wins. It's the only way to approach every game. So, you know, nothing changes."