Sam Allardyce hit out at a "diabolical" missed foul on Wilfried Zaha in the 3-1 defeat at Southampton, before tipping Crystal Palace's relegation battle to go right to the wire.
Palace boss Allardyce bemoaned the assistant referee refusing to flag Steven Davis' heavy challenge on Zaha in the build-up to Saints' first goal at St Mary's on Wednesday night.
Maya Yoshida and James Ward-Prowse struck two goals in as many minutes to steal Saints a late victory, after Nathan Redmond and Christian Benteke had traded first-half goals.
Allardyce believes Palace face the toughest run-in of all the Premier League's relegation battlers - and challenged his side to keep a higher points tally than matches played to stay on course for survival.
"It's diabolical in terms of that decision on Wilfried Zaha," said Allardyce.
"I can't for the life of me find any reason why the assistant hasn't seen Wilfried in control of the ball being completely bowled over by the opposition player from behind.
"It just baffles me why he's kept his flag down, and how a professional at this level can get such a simple decision wrong.
"Some decisions are difficult, this wasn't difficult, it was so easy, and it cost us being 1-0 up at half-time.
"I don't want to get fined, but at the end of the day he deserves the criticism he gets for not making the right decision. But what can you do about it?"
Asked if he spoke to the officials about his grievance, Allardyce replied: "There's no point. He'll deny it was a foul.
"They get so superbly protected today, and perhaps rightly so because it is a hard job.
"I don't know if it would have changed the game. And it's our own fault we lost it after that."
Having surrendered their four-match winning streak on the south coast, Palace must now travel to Arsenal on Monday night.
Allardyce believes his men could well need a result at the Emirates in order to keep their survival bid on track.
"Our target is that we stay on more points than games played," said Allardyce.
"Which means if we can stay on more points than games played for the last eight games we'll get more than 38 points and that will be enough.
"We've got to get a result now otherwise we'll be 31 games, 31 points.
"We've got a game in hand, when that game comes round we'll have to get some points.
"That's why for me a point would have been like a win tonight.
"I think our relegation fight will go to the wire, yes.
"We've had a massive boost in the end by beating Chelsea, but everybody else is picking results up down there.
"You're in control of your games, you've got to get the points you need, and you can't go chasing looking at the results elsewhere and hoping they've lost because ultimately you'll fail.
"I think we've got the hardest run of all the teams down there, that's why a point would have been very precious here tonight."
Saints boss Claude Puel praised Shane Long's perseverance despite the striker missing three clear-cut opportunities in a testing night.
Puel also admitted Davis could have fouled Zaha in the build-up to Redmond's goal - but insisted his side could have had three penalties in the first half alone.
"Perhaps, but if we can see that then I think we can have three penalties in the first half," said Puel.
"If we start to see fault or no fault then that can do other things also for us.
"I kept going with Shane Long because I wanted him to get the reward of a goal for all his hard work.
"He did some fantastic work for the team."