MANCHESTER, England — Returning to the Liverpool dressing room, Juergen Klopp was savoring the unexpectedly smooth elimination of Manchester City.

Then the Liverpool manager was halted in his tracks.

There was even more stunning news from the Champions League on Tuesday night.

Just like Liverpool, Barcelona started its quarterfinal second leg with a three-goal advantage.

Unlike Liverpool, Barcelona conceded at home the previous week.

It proved costly for Barcelona. Roma required a 3-0 victory to oust the Spanish league leaders, and it was improbably accomplished to advance 4-4 on away goals.

"I walked up the stairs and somebody told me," Klopp said after Liverpool's 5-1 aggregate win over City. "I really thought it was a joke. Not that I don't respect Roma, the absolute opposite. They have a fantastic team. Edin Dzeko, wow."

Wow, indeed. It was Dezko's sixth-minute goal that signaled Roma's determination to overhaul Barcelona. The former Man City striker then earned the penalty that was converted by Daniele De Rossi, and it was game on.

"It was something almost impossible," Roma midfielder Radja Nainggolan said, "but in the end it became possible."

Kostas Manolas' header sealed Roma's first trip to the European Cup semifinals since 1984.

"They lost Mo Salah and they are in the semis," Klopp said. "That's quite a big thing."

Klopp is fully aware of that. Liverpool is through to the semis in part thanks to Salah with his nine goals in 12 European matches — the latest in the 2-1 win at City on Tuesday.

Roma reluctantly sold Salah last June. But the need to comply with UEFA financial fair rules meant the Italian capital club cashed in on its biggest asset. For Liverpool, paying 42 million euros (then $47 million) for the Egyptian forward now appears a bargain. It seemed more of a gamble at the time, given Salah had come off a season netting only once in his nine European fixture.

Now Salah's 39-goal haul this season is on a par with Barcelona forward Lionel Messi. Only one of them has a shot at picking up the European Cup in Kiev next month.

What seems remarkable is that both sides who reached the quarterfinals on Tuesday are far off the pace in their domestic competitions.

Liverpool trails Pep Guardiola's City in the Premier League by 17 points in third place. Roma is even worse off in Serie A, toiling away 21 points behind Juventus in fourth place.

At a time when UEFA is trying to address concerns about the levels of competition balance in its competitions, seeing Liverpool and Roma advance is a welcome tonic.

"This competition is quite fair," Klopp said. "I really think a normal final would have been Manchester City against Barcelona, and now they are both out."

The Italian leaders could join them on the Champions League scrapheap on Wednesday night, with Juventus trailing holder Real Madrid 3-0.

That could leave Bayern Munich as the sole league leader still in contention in Europe with the newly crowned Bundesliga champions holding a 2-1 advantage over Sevilla heading into Wednesday's second leg.

At stake is a place in Friday's UEFA draw alongside Liverpool and Roma. What the two clubs have in common are investors from Boston, Massachusetts. Liverpool owner John W. Henry also runs the MLB's Boston Red Sox, while Roma chairman James Pallotta co-owns the NBA's Boston Celtics.

"I'm on cloud nine," Pallotta said at the Stadio Olimpico. "But I'm more happy for the team that they get an opportunity to compete against the best teams, with only four left.

"And I'm happy for Rome, the fans are so great, it's good to see this. Fifteen minutes afterward I went outside and they're still singing. You don't get fans like that in too many places in the world."

Anfield is one of them — the potential next European destination for Roma.

Liverpool, which beat Roma in the 1984 final, will be contesting its first Champions League semifinal in a decade. For the five-time European champions, it will be the first trip to the last four with Henry running the club and Klopp in the dugout.

"What I would really like to do," said Klopp, who reached the 2013 final with Borussia Dortmund, "is to drink a beer and watch a Champions League game. Unfortunately, it is always work."