As Ian Happ dropped to his knees in clear pain on Thursday afternoon, Cubs fans surely held their collective breath. Chicago's lineup has gone through what has felt like a season's worth of ups and downs in this abbreviated campaign, but Happ has been a bright spot.

The good news that came out of the Cubs' 6-2 loss to the Pirates was that Happ did not sustain a serious injury from the fluke foul ball that struck his right eye during his at-bat in the fourth inning. It was just a bruise. X-rays came back negative for anything worse, giving hope that the team's MVP to this point can be back in the leadoff spot soon.

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"Scary moment right there, where you think you might lose him," Cubs outfielder Kyle Schwarber said. "But it sounds like it's good news."

The Cubs will monitor Happ's progress Thursday night and pregame Friday, when the North Siders open up an important five-game series with the Cardinals. The rival clubs are slated to play a doubleheader Saturday in a wrap-around weekend set that ends with a Labor Day matinee on Monday.

"All indications, I heard, it's not too bad," Cubs manager David Ross said. "So, we'll see. I'll see how he's feeling. Obviously, that's a sensitive area and we've got to make sure he's all right. I'll check in with him."

The other side of the coin Thursday was that the Cubs' lineup experienced one of its off games to finish off this 10-game, 11-day swing through Detroit, Cincinnati and Pittsburgh with a 5-5 record. A surplus of missed opportunities sent the National League Central-leading North Siders (22-15) to the loss column.

That included in the third inning, when Happ slashed a pitch from Pirates righty JT Brubaker into the left-field corner for a double to put two on with no outs. Chicago wound up with only one run in the frame, then squandered a bases-loaded opportunity in the sixth. The Cubs finished the game 1-for-9 with runners in scoring position.

In the previous nine games on the trip, Cubs hitters launched 22 homers (2.4 per game), scored 55 runs (6.1 per game) and posted an .817 OPS. That type of support, however, was missing this time around for Cubs righty Alec Mills, who gave up four runs (three via a homer by Bryan Reynolds in the third inning) in his five frames.

"For sure, we had some chances to add some runs early on and didn't do that," Ross said. "That'll catch up to you at some point."

With two outs in the fourth, Happ swung at a 2-2 breaking ball from Brubaker and chopped the pitch into the ground. The baseball bounced up and struck Happ near his eye, sending the Cubs' center fielder to the ground.

Happ was swiftly met by head athletic trainer P.J. Mainville and was on his feet after a few moments, but Chicago lifted the outfielder from the game. Cameron Maybin, who grounded out after finishing the at-bat for Happ, took over in center.

"Scary. Vision's not something you want to mess with," Cubs first baseman Anthony Rizzo said. "There's the initial shock factor for him and you're hoping, give him a couple minutes and everything's fine."

Ross said there was no discussion of trying to have Happ stay in the game. The manager said the outfielder's vision was blurry and the area struck by the baseball quickly began to swell.

"You could tell right where it hit him," Ross said. "It's tough to hit with two eyes, much less one."

And the Cubs can ill afford to take any chances, given how well Happ has played.

Through 37 games this season, Happ has been the Cubs' top offensive performer, hitting .311/.421/.648 with 10 homers, 22 RBIs and a team-leading 22 walks. He entered Thursday tied for fifth in the Majors with 1.9 WAR (per Fangraphs).

"I can't speak enough about the guy right now," Schwarber said. "The way he's swinging the bat, playing defense, working professional at-bats every time."

Happ's play has helped shore up the top of the lineup, while the likes of Kris Bryant, Javier Báez, Willson Contreras and Rizzo have continued to work on getting out of offensive lulls.

"He seems to be in good spirits," Rizzo said of Happ after the loss. "I don't think he's seeing Tweety Bird right now, luckily. But, it's scary, especially with Happer and how he's carried us this year."