CINCINNATI -- Cole Hamels fired a warm-up pitch to Cubs catcher Willson Contreras, finished his follow through and immediately made a right turn off the mound on Friday night. Manager Joe Maddon looked up from his notes in the third-base dugout, saw the veteran leaving the field and thought the worst.

"When a guy's walking at you like that, such a professional," Maddon said, "you have no idea where this is going to go."

If there was a sliver of good news in the wake of Friday's 6-3 loss to the Reds, it was that Hamels' left arm was not the problem. That is about as far as the silver lining stretches, though. Hamels sustained a left oblique strain and will be placed on the 10-day injured list prior to Saturday's game at Great American Ball Park.

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The Cubs did not make any official moves after Friday's defeat, but the expectation is that the team will reach down to Triple-A Iowa for a pair of reinforcement arms. Following the loss, several teammates approached veteran outfielder Carlos González and offered a handshake or a hug. A few huddled around his locker to talk. He would need to be designated for assignment to vacate a roster spot.

On the opposite end of the visitors' clubhouse, Hamels explained that he felt a cramp-like sensation in his left side on an 0-1 cutter to Scooter Gennett in the first inning. The pitcher did some stretching between innings and walked around, hoping the discomfort would subside. The brief warm-up on the mound before the bottom of the second made it clear that the injury was not going away.

"It was grabbing again," Hamels said. "So, I just knew that that's not always good. You can definitely injure yourself a lot more by trying to play through it."

Hamels knows that from experience, too.

As Friday's setback was happening, Hamels was able to reach back into his memory bank to 2017, when he tore his right oblique in a late-April outing against the Twins. The lefty described that as the one where ¡°you feel like you just got shot." Based on that alone, Hamels is hopeful that this injury will not be as serious as the one that cost him two months of the season two years ago.

Hamels still needs to undergo an MRI exam and consult the Cubs' medical staff to learn the severity of the injury.

Given that the National League Central-leading Cubs are in the thick of a division race, Hamels also does not want to have a repeat of what happened after the oblique strain in 2017. He felt he returned a week too soon and the lefty was inconsistent for the rest of that season and deep into the '18 campaign, while battling mechanical problems that stemmed from the injury.

"I want to make sure I come back and everything's the way it should be," Hamels said, "the way that I'm used to doing it and the way I've been playing, so that I can make a difference. Otherwise, it's a waste. So, I think it's just a matter of really getting the best information from the doctors of the severity of it and then going through the right type of therapies to make sure that I'm good to go."

The 35-year-old Hamels threw 22 pitches in the start against the Reds, allowing one run on two hits with a walk and a strikeout in the first inning. Following his exit, Maddon turned to left-hander Mike Montgomery as an emergency reliever and the pitcher allowed a first-pitch home run to Phillip Ervin in the second. Montgomery went on to allow five runs over 2 1/3 innings for Chicago's short-handed 'pen.

"It's unfortunate," Montgomery said. "I hope everything's going to be all right with Cole. You're ready physically [to enter the game] and I think mentally you¡¯ll be ready as best you can. But, at the end of the day, I just didn't make the pitches. It's just one of those things where you've got to just chalk it up and move on."

Hamels had been brilliant so far in June with a 1.00 ERA and 36 strikeouts in 36 innings in five starts prior to Friday's setback in Cincinnati. On the season, Hamels has gone 6-2 with a 2.98 ERA in 17 starts, amassing 97 strikeouts against 35 walks in 99 2/3 innings for the Cubs, who picked up his $20 million team option over the winter.

Before the game, Maddon sang the praises of Hamels, expressing that he felt the lefty deserved to be in the conversation for the NL All-Star team. Hamels is a four-time All-Star -- most recently in 2016 -- and said he was looking forward to the opportunity, especially because he probably would appreciate it more now than he did when he was younger.

"As you get older in this game," he said, "you want to enjoy some of the things that you might not have taken so seriously when you were early in your career. You take things for granted. So, that'll kind of be something that could be tough. It is. Pitchers are a little bit different, because they get selected on necessity as opposed to popularity. So, this could easily deter even the opportunity. It's a tough thing."

Chicago's rotation is also missing right-hander Kyle Hendricks at the moment. Hendricks has been on the 10-day injured list due to a right shoulder impingement since June 15. Without Hendricks -- who is slated for a 45-pitch mound workout on Saturday -- the Cubs have been using righties Adbert Alzolay and Tyler Chatwood as the fifth and sixth starters.

Alzolay is scheduled to pitch on Monday in Pittsburgh, and there is a strong chance that Chatwood slots in on Wednesday in place of Hamels. Hendricks could return before the All-Star break, but that is still up in the air. Hamels said it is at least good that Chicago has depth right now.

"It's great to be able to have [Alzolay] and still have him here. And even Chatty," Hamels said. "It's good to have those types of guys that can fill in and still get the job done. And we're going to get Kyle very quickly, hopefully. And then we do have [the All-Star] break. That obviously helps"

What did not help was the image of Hamels walking off the hill so early in the evening.

That was surely a mental blow for a Cubs team trying to find its footing.

"When Cole walks off the mound," Maddon said, "that can be deflating."