Three quick thoughts from Roma's incredible 3-0 win against Barcelona in the Champions League at the Stadio Olimpico, which sees the Italian side advance on away goals after the aggregate score of this quarterfinal finished 4-4.

1. Roma stun Barcelona to reach semis

Kostas Manolas scored 10 minutes from time as Roma turned around a three-goal first-leg deficit to dump Barcelona out of the Champions League on Tuesday.

Few gave Roma a chance after they lost the quarterfinal first leg 4-1 at Camp Nou last week, but Barca coach Ernesto Valverde warned that "extraordinary" things can happen in football when he previewed the game on Monday. Perhaps he was aware his team have been stuttering in recent weeks. Perhaps he was just referencing Barca's very own comeback against Paris Saint-Germain last year. This time it was their turn to be embarrassed.

Edin Dzeko's early opener and Daniele De Rossi's second-half penalty gave Roma a 2-0 lead on the night and pulled them back to 4-3 on aggregate with more than half an hour to play.

Barca were rocking in the exact same way PSG did against them last year. There was no composure. For a while it looked like they might cling on as Marc-Andre ter Stegen made save after save to keep them in front, just.

But the goal was coming. The home supporters, electric all night, could feel it. It eventually arrived in the 81st minute, Manolas flicking home from a corner to complete a barely believable turnaround.

It was Barca's first defeat in either La Liga or the Champions League this season, but it couldn't have come at a worse time. For the third year running, they fall out of Europe at the quarterfinal stage. They will have few complaints about the manner of their elimination.

Roma always looked likely to go through from the moment Dzeko held off Samuel Umtiti and Jordi Alba to open the scoring. Coach Eusebio Di Francesco named an attacking team and they quickly set out their stall, Dzeko's goal arriving inside the first 10 minutes.

They will have been disappointed, after registering 10 shots, to have ended the half only one goal ahead. It didn't affect their belief, though.

Dzeko, terrific throughout the 90 minutes, was involved in the second goal, too. He got in behind the Barca back line and was fouled by Gerard Pique. The penalty, after a slight delay, was given and De Rossi drove home.

Chances came and went for Roma, with Ter Stegen making a great save from Stephan El Shaarawy to keep Barca's noses in front. He could do nothing when Manolas' header flashed across him moments later, though.

For the third straight year, Barcelona were eliminated from the Champions League in the quarterfinals. Michael Regan/Getty Images

Barca finally came alive. Or, at least, they attacked. Ousmane Dembele came on and Lionel Messi, isolated in both legs by Roma, became more involved. But it was too late. Roma had done it.

2. Barca's luck runs out

The numbers have been good for Barcelona this season: one defeat in their past 48 games before Tuesday, unbeaten in La Liga, unbeaten in the Champions League, a Copa del Rey final to come later this month.

However, there have been worrying signs for a number of weeks. Their 4-1 aggregate win against Chelsea flattered them in the round of 16, but things have really regressed since the international break.

They struck it lucky against Sevilla, drawing 2-2 with two late goals, and comfortable wins against Roma and Leganes weren't as comfortable as they looked.

Their first-half performance in Rome was a throwback to last season's dismal showing away against PSG and Juventus. Even with Sergio Busquets back in the side, they simply couldn't cope with the Serie A side's pressing. Busquets, Ivan Rakitic and Andres Iniesta were unable to move the ball forward, and behind them there was chaos. So often Barca's strength this season, the defence looked like they were playing together for the first time.

Umtiti and Alba were bullied by Dzeko for the opening goal. Things didn't improve after that wake-up call, either, as the Roma chances kept coming. Barca could do nothing to turn the tide as the game progressed. Even Messi, so often their superhero, couldn't do anything about this one.

Their Treble dream is over. They now must win the league and the cup -- and even that might not be enough if they have to endure more Real Madrid success in Europe.

3. Di Francesco engineers Roma's miracle

The Stadio Olimpico was rocking with belief before the game, and the Italian side's players took that energy on to the pitch. They were brilliant in the first half, swarming all over their Catalan counterparts, and will have been disappointed to have been only one goal ahead at the break.

There was no disappointment by the time the final whistle went, mind. Di Francesco got it right. Really right. Dzeko was brilliant, Radja Nainggolan was everywhere and Federico Fazio ... what was he doing as a right-wing-back?

It looked as if the damage had been done last week at Camp Nou. Two own goals, sloppy defending and a lack of belief in the first half had proved their undoing. However, hindsight won't force them to think what could have happened if they'd played with more courage in the first leg.

Could they win the tournament? The odds are still stacked against them, but they're potentially three games away from doing the unthinkable. No one thought they would knock favourites Barca out, after all.