Roma defeat reinforces the need for Barca changes in the summer.

Barcelona's shock Champions League exit at the hands of Roma on Tuesday does not discount what is likely to be a double-winning season but the loss should serve as a warning for what comes next.

After the 3-0 defeat at Stadio Olimpico, which sent Roma through on away goals, Ernesto Valverde paid lip-service to shouldering responsibility but in the same breath pointed to a disappointment with his players.

"A week ago we scored four goals with the same line-up," Valverde said. "We coped with their game and played ours. It went right. This time it did not."

But perhaps that was part of the problem. Barca won 4-1 at the Camp Nou with a performance that did not deserve the result.

Two own-goals and a late Luis Suarez strike masked what had been a disjointed display, low on fluency, high on mistakes, which on that occasion went unpunished.

Of all the trailing teams heading into the quarter-final second legs, few would have predicted Roma to be the ones celebrating progress to the last four. But there were clues, and Valverde missed them.

Barca have flattered to deceive in recent weeks.

They were outplayed for large spells by Chelsea at Stamford Bridge but snatched a 1-1 draw. A 1-0 win at home to Atletico Madrid, which all-but secured them the title, was efficient rather than emphatic, decided only by a stunning Lionel Messi free-kick. And against Sevilla a fortnight ago, Barca trailed 2-0 in the 87th minute before Suarez and then Messi, as a substitute, engineered a dramatic late escape.

"Without personality, without playing well, without Messi and without cause for disagreement, Barca were shipwrecked in the Olimpico against an immensely superior team that knocked the Barca players off an artificial pedestal," wrote Madrid's daily newspaper AS on Wednesday.

Perhaps that is too strong.

Barca are still unbeaten in the league - although with what now appears an even trickier game at home to Valencia on Saturday - and 11 points clear at the top.

If they overcome out-of-form Sevilla in the Copa del Rey final later this month, they will likely be toasting a domestic double at the end of the season, possibly as La Liga's first ever invincible team.

But Roma's triumph, ensuring Barca's third straight quarter-final exit in Europe, should at least serve as a wake-up call, reinforcing the need for changes in the summer.

Andres Iniesta admitted he might have played his last Champions League game as he ponders a move to China. He would need to be replaced or, more likely, properly succeeded by Philippe Coutinho.

- Lack of flexibility -
Sergio Busquets played through the pain of a toe injury, exposing Barca's lack of a competent back-up for the Spaniard in central midfield, which will have to be addressed.

Samuel Umtiti's future needs to be resolved, as stalling contract talks have affected his form, and there is room for improvement at right back, where Sergi Roberto has not convinced.

But Valverde must also acknowledge a lack of flexibility, born largely out of his own tactics.

Resilience, organisation, an excellent goalkeeper in Marc-Andre ter Stegen, and Messi, have taken Barca a long way this term but when they needed to adapt against Roma, they were found wanting.

"They played their game and we did not know how to react," Busquets said. "We did not know how to create chances. We weren't in the right positions and in the end, they got the result."

Victory over Valencia, who sit third, ahead of Real Madrid, will quickly change the mood. Barca are on the cusp of breaking Real Sociedad's 1980 record of 38 unbeaten league games, set in a run that stretched across two seasons.

But even with successes still to come, they would do well to let the rout in Rome linger a little longer.

"You have to endure the pain - there will be some tough days," Valverde said.

"We have to try to win the two competitions. A defeat like this hurts a lot, but you have to look forward."