Moments after Dansby Swanson struck out for the final out in Monday’s 5-3 loss to the Pirates, the Wrigley Field air was filled with a fitting tune from the Wrigley Field organist.

A rendition of Katy Perry’s “The One That Got Away” played while 33,583 fans made their way out of the Friendly Confines — an apt tune for a night that started with so much promise and ended feeling like the Cubs had let a golden opportunity slip through their fingers.

The Cubs were cruising — a 3-run lead, their starter, Jameson Taillon, dealing and a bullpen with rested leverage arms had the Cubs feeling good about extending their season-high 6-game winning streak.

“It feels like a loss, yeah,” Counsell said after the game. “I mean we lost. We didn’t get it done tonight. Back at it tomorrow.”

A win on Monday would have meant the Cubs pulling to within 2.5 games of the final NL Wild Card spot. Instead, they sit 3.5 games back with 24 games left — and don’t hold the tiebreaker with Atlanta, who holds the final playoff spot.

It was a bucket of cold water on the Cubs who were scorching hot and had looked practically untouchable over their 9-game road trip. In that span, they amassed an 8-1 record and clawed their way back into the playoff conversation — something that seemed miles away even when the team embarked on the trip out East.

“We know we have to play at a really high level because we’ve got significant ground still to make up,” Counsell said before the loss. “But we’ve also — in a sense — earned this, and we’ve earned the right to have some fun this month and to play some good baseball and see what happens.”

Eight pitches after Taillon exited, the mood had changed to disbelief.

[WATCH: Jameson Taillon brilliant in scoreless quality start]

Counsell turned to Jorge López who had been terrific since being signed as a minor league free agent earlier in the summer. In 21 appearances with the Cubs entering Monday, López had a 0.76 ERA and had allowed just 3 home runs in 26.1 innings.

“[López has] been wonderful,” Counsell said. “He’s pitched wonderfully. He obviously didn’t have a good night tonight. But that was the decision, and it was an easy decision.”

But, in the 8th inning, López allowed a pair of soft singles and then a 3-run shot to Bryan Reynolds to tie the game. Two batters later, Andrew McCutchen homered to give the Cubs the lead.

“I felt great,” López said. “I feel it was snowballing and I just couldn’t execute the next couple of pitches. It’s tough. I’ve been doing good for the last two months. It’s unfortunate to have these [four] runs and give the win [to] them.

“It’s something — you don’t expect that, the way we’ve been playing. We were trying to take from the road trip, get in here in front of our home [crowd] and unfortunately it’s just another day. We lost. Just come in tomorrow and do it better.”

The Cubs offense — which had been otherworldly entering Monday came crashing back to earth. After jumping out to a 3-0 lead in the 5th, the Cubs mustered just 3 baserunners over the last 4 innings and stranded a leadoff, Nico Hoerner double in the 7th inning.

That was a stark contrast from how the Cubs bats performed against the Pirates relief corps a week ago in Pittsburgh. In 14 innings against Pittsburgh relievers, the Cubs scored 30 runs (28 earned) across three games and a 1.120 OPS. Monday, the Cubs were 0-for-8 against the Pirates’ bullpen.

“They pitched well,” Counsell said. “Their bullpen had a couple of good innings, for sure.”