Chelsea's defeat in the first leg of the Champions League last 16 tie in Naples leaves them on the brink of elimination from the competition and means they have now gone five matches without a win.
With Arsenal facing a 4-0 deficit in their second leg at home to AC Milan next month, England now faces the very real prospect of failing to have a team in the quarter-finals for the first time since 1996.
Chelsea can still turn the tie around in the second leg at Stamford Bridge on March 14 and are lucky to still have the chance after a late goal-line clearance by Cole, who came on as an early substitute for the injured Jose Bosingwa.
Whether Villas-Boas is still Chelsea's coach by the time Napoli come to London was the subject of some heated debate in Wednesday's English media, with reports saying he omitted the big names because of a dressing-room power struggle.
Although he is still talking confidently about his three-year project to rejuvenate Chelsea's ageing team, his billionaire boss Roman Abramovich is not noted for patiently tolerating failure.
"Speculation will continue as the results don't happen," the 34-year-old Portuguese said.
"We have to solve these mistakes at the back. We need this concentration right and this efficiency right, for sure."
BAD DAY
A day that began badly for Chelsea with news that skipper John Terry needs surgery on a knee injury and is likely to be out for between six to eight weeks ended with them trudging off the San Paolo pitch with Villas-Boas looking stunned.
Chelsea started a roller-coaster match the better of the two sides and went ahead after 27 minutes when Juan Mata capitalised on a mistake by Paolo Cannavaro to pick his spot.
But Napoli responded with goals from Ezequiel Lavezzi and Edinson Cavani before halftime, with Lavezzi scoring a third midway through the second half to put Napoli in command of the tie as Chelsea's shocking defensive lapses continued.
"At the moment, without John, a very important player for the team, we have suffered a lot of goals recently. We had improved a lot at the beginning of January, so we have missed John," Villas-Boas added.
"But we have full belief in these players and we have to continue to work with them to get it right."
David Luiz, who has suffered a torrid time during an unhappy season, gifted Napoli their third goal with Chelsea defending like a parks team.
"It's obvious that the player has become a target," said Villas-Boas.
"He's a fantastic young player with a big future ahead of him, and he has to work to try and be a bit better. We suffered three goals. If he's linked to one, he might not be linked to the other two."
It was not only what happened on the pitch that is so alarming to Chelsea's increasingly disgruntled fans, who have been accustomed to their team winning things since Abramovich bought the club nearly nine years ago.
