BOX SCORE

CHICAGO — Still riding the high of Sunday’s walk-off win, there was no reason to believe the Cubs couldn’t keep the momentum going.

Michael Soroka was on the mound for his highly anticipated debut, and the Cubs have put in some big performances against the Cincinnati Reds this season.

But some tough luck plagued the Cubs, and a 3-2 loss to the Reds was the result in the opener.

Here are three things we learned:

What just happened? 

Soroka was on a roll in his Cubs debut. He notched three strikeouts in the first inning, pitching around a walk to halt any threat of damage from the Reds’ offense. 

In the second inning, he allowed the first hit of the game for either team — a solo shot to the left field bleachers from Tyler Stephenson. 

But disaster struck in the Cubs’ offensive half of the inning when Soroka could be seen leaving the game with a trainer. Ben Brown began warming in the bullpen and replaced his new teammate for the third inning. 

The Cubs later announced Soroka left his start with right shoulder discomfort. 

It’s a huge blow for the Cubs, who acquired Soroka ahead of the trade deadline in hopes of bolstering a rotation that’s dealt with injuries the entire season. 

Amid all the madness, the Reds were dealing with a starter situation of their own: Nick Lodolo, who retired the first five Cubs he saw in order, left the game after 1.2 innings with a blister on his left finger. 

Ben to the rescue

Ben Brown was probably not expecting to come into the game in the third inning. 

He was ready regardless. 

Brown has struggled with his command this season, entering the game with a 6.22 ERA over 88.1 innings pitched. But on Monday night, he was pretty dominant. 

The 25-year-old right-hander struck out five over four innings of relief, allowing one run on two hits. The run was initially scored as unearned, due to Ian Happ bobbling Elly De La Cruz’s double in left. It was later changed to an RBI for De La Cruz with the runner advancing to third on the throw. 

Brown threw 56 pitches, 36 of them for strikes, while touching 97 mph with his fastball. The outing lowered his season ERA to 6.04.

High highs and low lows

Dansby Swanson gave the Cubs the lead in the third inning with a two-run, 415-foot blast. It was his 17th home run of the season, and the Cubs looked to be back on track for a win with Lodolo out of the game as early as he was. 

However in the bottom of the seventh, as the Cubs trailed by a run, Swanson looked to come up with a clutch infield single — very similar to the one he hustled out in the bottom of the ninth Sunday — and score Willi Castro to tie the game. 

But after the Reds reviewed the play, the worst was revealed for the Cubs: Swanson missed the bag completely, even though he would have been safe by a decent margin had he touched it. 

The result? Inning over, and Cubs still trailed by a run late — a huge momentum swing that deflated their winning chances.

The series continues on Tuesday at 7:05 p.m. CT with Shota Imanaga (8-4, 3.25 ERA) taking the mound for the Cubs. Reds right-hander Zack Littell (8-8, 3.58 ERA) will start for the visitors. 

Coverage begins at 6 p.m. on Marquee Sports Network.Â