They were written off when they lost the first leg of their quarter-final against Porto 3-1. So at least Bayern Munich have something to hold onto.
But trying to overturn a three goal deficit against Barcelona is an altogether different proposition.
Especially when Lionel Messi is liable to turn on his extra-terrestrial talents.
In the prelude to the clash Messi’s former manager Pep Guardiola – now leading Bayern – said there wasn’t a system that could arrest Messi.
The 27-year-old vindicated his old mentor’s fears in three devastating minutes near the end of the first-leg at the Camp Nou.
After 77 minutes Messi fired a low shot home from the edge of the area.
Then his pièce de resistance. Receiving the ball 30 metres out, he surged past a befuddled Jerome Boateng and dinked the ball over the imposing figure of Manuel Neuer.
Up until then the Bayern keeper had kept Barca at bay with a series of impressive saves.
To be beaten by a chipped ball over the body is one of the ultimate ignominies for a goalkeeper. And that will haunt Neuer for days.
To attempt such a gesture against a keeper of Neuer's class highlights the destructive impudence within Messi. In front of millions watching on TV screens throughout the world, he won the the battle of nerves in that one-on-one.
That Neymar rounded Neuer to slot in Barca’s third in stoppage time will only exacerbate the German goalkeeper's nightmares.
Guardiola won 14 trophies in four years at Barcelona. Messi, aided by the midfield genius of Andres Iniesta and Xavi Hernandez was the jewel in his crown of talents. Hothoused at the Barca training centre La Masia, they were the bedrock of the Barcelona way: gluttonous amounts of possession, short passes, technical brilliance and comfort on the ball.
That was then.
Barca’s current boss, Luis Enrique, has rebooted Barca to fit into the modern world. The Brazil star Neymar and the Uruguayan international Luis Suarez have been added to remove the weight and expectation from Messi. He and they have flourished.
Last weekend the South American troika accounted for six of Barca’s goals in the 8-0 destruction at Cordoba in La Liga.
On Wednesday night in front of nearly 96,000 fans they scored three. That brings their tally up to 111 in all competitions this season.
Barca host Real Sociedad on Saturday before the Champions League second leg in Munich on 12 May.
The Bayern midfielder Thomas Mueller says his side's supporters should not expect another miracle fightback, as they saw against Porto.
"The 11 guys on the pitch will give their all once more until the last second," he said. "We have to stand together as a team. We are FC Bayern and we'll keep our heads up."
They don't really have much choice.
"They completely fell apart and that should have never happened," fumed Bayern's honorary president Franz Beckenbauer. "It would be a sensation now to turn this around."
Bayern's aspirations of a treble to emulate the feat of 2013 lies in ruins in a little over a week. On 28 April they lost their German Cup crown after a defeat in the semi-final against Borussia Dortmund.
While it is still possible for Bayern to progress in the Champions League, they need a result similar to Deportivo La Coruna's 4-0 rout of AC Milan, having lost the first-leg 4-1 in Italy, in the 2004 quarter-finals.
But no side has ever come back from losing the first-leg 3-0 in the semi-final of the Champions League or European Cup especially against Barcelona.
"We did well for a long period," reflected Guardiola. "We wanted to control the game and keep the ball away from Barcelona as much as possible and we did that.
"But Messi simply made the difference and it's a pity we conceded the third goal.
"The return leg will now be complicated, but we will fight hard."
"The last drop of hope is the game against Porto," added Neuer. "Never say never."
Or perhaps, in Neuer's case, never say: "Messi's not going to chip me 10 yards from goal."