Chelsea coach Liam Rosenior launched a scathing rebuke of his players as their season slumped deeper into crisis with a 3-0 defeat to Brighton on Tuesday.
The result leaves Chelsea seventh in the Premier League and seven points adrift of fifth-place Liverpool having played a game more.
The top five qualify for the Champions League, but with just four more rounds of the season to go, Chelsea are on the verge of being cut adrift.
Chelsea have now lost five league games in a row without scoring a goal for the first time since 1912 -- the same year the Titanic sank.
Rosenior was the subject of X-rated chants from the disgruntled away end during the second half of a toothless display in which his team failed to register an attempt on target.
Asked whether the performance was the worst of his tenure, the former Strasbourg boss told Sky Sports: "By far. It was unacceptable in every aspect of the game, unacceptable in our attitude.
"I keep coming out and defending the players. That's indefensible, that performance tonight.
Liam Rosenior apologized to Chelsea fans following the team's loss at Brighton. Darren Walsh/Chelsea FC via Getty Images "The manner of the goals we conceded, the amount of duels that we lost, the lack of intensity in the team. Something needs to change drastically right now.
"The professionalism wasn't there. It's a really difficult night. The most difficult night not even just here, so far, at this magnificent football club, but in my career.
"Some of the things I witnessed today, I never want to see again."
Goals from Ferdi Kadioglu, Jack Hinshelwood and Danny Welbeck at the AMEX Stadium did not reflect Brighton's dominance on the night. Victory saw them leapfrog Chelsea and move up to sixth in the standings and boosted their own pursuit of European soccer next season.
It was a seventh loss in Chelsea's past eight games in all competitions. The team that was crowned Club World Cup champions less than a year ago has won only one of its past nine.
While they have an FA Cup semifinal against Leeds on Sunday, their campaign has unraveled in recent weeks, including elimination from the Champions League at the hands of Paris Saint-Germain.
"We need to look in the mirror; I need to look in the mirror," said Rosenior, who was without attacking trio Cole Palmer, Estêvão and João Pedro due to injury.