Once unbeatable Barcelona is wondering where it all went wrong.

The team that only a few weeks ago celebrated a streak of 39 games without a loss is now lamenting elimination from Europe's most important club competition.

The Spanish giant was ousted by rival Atletico Madrid in the quarterfinals of the Champions League on Wednesday after its third loss in four games - a 2-0 defeat at the Vicente Calderon Stadium that erased its 2-1 first-leg win at the Camp Nou.

The result ended Barcelona's chances of repeating the treble of Champions League, Copa del Rey and Spanish league titles - its biggest goal entering the season.

The loss also further dented the confidence of players who looked unstoppable not long ago. Lionel Messi, Luis Suarez and Neymar - the trio of world-class strikers that are capable of scoring at will - have been far from great recently.

"Our objectives are always the highest, we are proud that Barcelona always aims to win everything," coach Luis Enrique said. "But we must accept this result and try to improve. We have two competitions left now, with a great chance to win them. They are two attractive goals to aim for. For any other coach in world, winning those two would be enough. But we must improve."

Barcelona is left with the Spanish league and the final of the Copa del Rey, which will be played against Sevilla in May.

Winning the league seemed like a certainty for the Catalan club a few rounds ago, but with the team's recent struggles, not even that is guaranteed.

Barcelona held a nine-point lead over Atletico less than a month ago but the gap has dwindled to only three points after a draw and two consecutive losses, including one at home to Real Madrid, which is four points back and also in contention.

"It's obvious we aren't at our best at the moment," Luis Enrique said. "Especially if you consider the level we have been playing at this season. But that's football. We need to lift ourselves now."

Until a 2-2 draw at Villarreal in the league three rounds ago, Barcelona was cruising. The club had won 19 of 20 games, and the only winless result was a Copa del Rey draw at Valencia, when it played without the regular starters.

Since the Villarreal game, Barcelona's trio of high-profile forwards managed to score only two goals in four matches - both times with Suarez in the first leg against Atletico, after Fernando Torres was sent off in the first half.

Messi is enduring his worst scoring slump with Barcelona in five years. He's been held scoreless since a win over Arsenal in the round of 16 of the Champions League on March 16.

Neymar hasn't found the net in four games, since the Villarreal game in the Spanish league.

In the midst of the turmoil, Barcelona had to mourn the death of former idol Johan Cruyff, who passed away just before the 2-1 home loss to Real Madrid.

Veteran midfielder Andres Iniesta said there is no doubt the recent setbacks have affected the team's mindset.

"The dynamic is not positive right now. We have to find strength because what's left to be played is still important," Iniesta said. "It hurts to be going through this moment. It hurts a lot for all of us, but we have to keep working to try to win what's still left to be won."

Barcelona had reached the semifinals of the Champions League in seven of the last eight seasons, winning four titles in the last 10 years. The last time it failed to reach the semis, it also fell to Atletico, in the 2013-14 season.

The team's next game is at home against Valencia in the Spanish league on Sunday.