Liverpool manager Juergen Klopp said "slapstick" mistakes had undermined Liverpool's defence of their Premier League title and made it almost impossible for them to finish in the top four.
Liverpool cruised to the Premier League title last season but are sixth in the current campaign on 46 points, five points behind fourth-placed Chelsea with nine matches remaining.
"I like to be an optimist, but in the league it is almost impossible to qualify in the competition for the Champions League places that we have," Klopp told German newspaper Bild.
"At Tottenham Hotspur, Gareth Bale is now playing again, and they are also in the running. (Manchester) City and United, who are far away, Chelsea on the rise. Reaching Champions League through the league will be difficult."
Klopp said his side had paid the price for uncharacteristic errors.
"The opponent usually doesn't need a lot of chances against us because we make big mistakes, insane ones that can almost be described as slapstick," he said.
"On the other hand, we create a lot of chances, in the 'expected goals' we are still second behind City in the Premier League, but far from them in the ones we actually scored. This problem has been going on throughout."
Liverpool are still in with a chance of winning this year's Champions League and are in the draw for the quarter-finals after brushing aside RB Leipzig in the last-16.
Missing out on Europe's elite club competition would be a huge blow but Klopp said he was not worried about his future.
"It would mean a huge financial loss. In almost all clubs, I would be questioned in a situation like this," he said. "This is normal, I accept that.
"Our owners, sports director nobody doubts anyone here. We have accepted the situation and fight our way through."
Liverpool next visit Arsenal after the international break on April 4.
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