Chelsea's troubles worsened after sloppy defending led to a 3-1 loss at Napoli in the last 16 of the Champions League on Tuesday, and nine-time winner Real Madrid was held to a 1-1 draw at CSKA Moscow.
Chelsea, which has slipped to fifth in the Premier League, threw away a 1-0 lead in the first leg in Italy when Ezequiel Lavezzi scored twice and Edinson Cavani added another goal.
It was also a disappointing night for former Chelsea manager Jose Mourinho, whose Madrid side failed to take its dominant domestic form into Europe.
Cristiano Ronaldo put Madrid ahead with his 36th goal of the season, but CSKA midfielder Pontus Wernbloom scrambled the ball into the net with the last kick of the match in the third minute of stoppage time to equalize for the Russian club.
While Madrid holds a 10-point lead over Barcelona to be on course to win the Spanish league, Chelsea has now failed to win for a fifth straight game in all competitions.
Chelsea manager Andre Villas-Boas gambled by not starting with Frank Lampard or Michael Essien, while captain John Terry was ruled out just before the match as he requires knee surgery.
Luck, however, was initially in Chelsea's favor with Juan Mata's opening goal somewhat of a gift from Napoli.
After being picked out by Didier Drogba, Daniel Sturridge's resulting cross was inexplicably mis-kicked by Napoli captain Paolo Cannavaro back toward his own goal. The ball fell perfectly for Mata to slot into the net past goalkeeper Morgan De Sanctis in the 27th minute.
Napoli leveled 11 minutes later when Lavezzi collected the ball on the edge of the area, eluded Chelsea midfielder Raul Meireles, before curling it into the bottom right corner past goalkeeper Petr Cech's outstretched hand.
Cavani, whose goals helped to eliminate Premier League leader Manchester City in the group stage, scored his fifth goal in seven Champions League appearances this season right on halftime when he turned Gokhan Inler's cross into the net from close range.
"We had a chance to go 2-0 up and a couple of defensive mistakes that against Napoli, with their attacking strength, will get punished,'' Villas-Boas said.
After Chelsea defender David Luiz gave the ball away sloppily, Cavani turned provider, squaring it past an outrushing Cech for Lavezzi to slot into an empty net in the 65th.
"We always say we keep working hard on the training ground but unfortunately we don't seem to transport that on the pitch,'' Cech said. "We have quality players who can turn it around, but it could be better because we don't have time to recover. We have a lot of games coming up and we are not in a position to drop many points in league.
"It's not an ideal situation but we are still in the Champions League and we will fight to the end.''
Chelsea left Italy with a crucial away goal, as Madrid did from Russia.
Ronaldo's 28th-minute goal had appeared to put the visitors on course for victory in a match played in subzero temperatures and on an artificial turf.
The Portugal forward pounced after the hosts had failed to clear Fabio Coentrao's cross from the left, striking the bouncing ball into the net with his less-favored left foot.
But Madrid paid for its failure to put the game away. CSKA goalkeeper Sergei Chepchugov saved Sergio Ramos' header in the 76th, before an unmarked Ronaldo inside the area rolled his shot just wide of the post with the goalkeeper beaten.
"We had our chances, especially in the second half, but we didn't convert them,'' Mourinho said.