The Works Eleven were also knocked out of the German Cup one week ago by second tier Kaiserslautern and a 2-1 home loss to Schalke 04 on Saturday left them in danger of surrendering second place in the Bundesliga.
Yet, only a few weeks ago, there were genuine hopes that the club could finally lay their “Neverkusen” tag to rest.
Leverkusen had taken 37 points from their opening 17 Bundesliga games, their second-best performance in the first half of a season, and a win over Borussia Dortmund even had them believing they could overhaul runaway Bundesliga leaders Bayern Munich.
Team captain Simon Rolfes declared that “the championship is possible” and the club’s website claimed that “the second half of the season promises to be full of exciting highlights.”
But even at that point, there were reasons to be apprehensive.
Coach Sami Hyppia’s nerves were left in tatters after a 5-3 home win over Hamburg which critics described as “kindergarten football” and a 5-0 home defeat by Manchester United in the Champions League was another ominous warning.
Sure enough, Bayer were again torn apart by top level opposition on Tuesday, suggesting they had performed above themselves in the first half of the season rather than underperformed since January.
Defender Emir Spahic had a nightmare match, giving away the penalty that led to PSG’s second goal and then getting sent off for a foul on Lucas.
Rolfes lost possession at the start of the move which led to PSG’s first goal after only three minutes and was substituted at halftime as was South Korean forward Son Heung-min while the usually prolific Stefan Kiessling cut a lonely figure in attack.
It was a similar story two years ago when they were hammered 10-2 on aggregate by Barcelona at the same stage of the competition.
In fact, Leverkusen fans know the routine almost off by heart.
Their team have never won the Bundesliga, but finished runners-up four times between 1997 and 2002 when they famously lost a five-point lead in the championship’s closing stages and were beaten in the Champions League and German Cup finals.
In 2009/10, they enjoyed the longest unbeaten start to a Bundesliga campaign when they went through their first 24 matches without losing, but again failed to win the title, and there was another second-place finish in 2011. Their only major titles are the UEFA Cup in 1988 and the German Cup in 1993.
“You can’t say that it all went wrong. You also have to look at what kind of team we faced. Paris are a top-class opponent and they were excellent,” Hyppia said.
“It’s a difficult phase,” he added. “We must be mentally strong like a boxer who has suffered a knockout punch and gets up again.”
Sporting director Rudi Voeller, who earlier this season had lambasted critics for talking down his club, suggested Paris St Germain might have been bridge too far for Leverkusen’s somewhat limited squad.
“That sort of defeat really hurts,” he said. “We are all downcast.
“But we know that in the last 16, we are pushing our limits against various teams. It’s a question of quality.”
(Writing by Brian Homewood in Milan; Editing by Rex Gowar)