Liverpool had no answers to Oldham in the FA Cup on Sunday, joining a lengthy list of Premier League teams to exit at the fourth-round stage of the world's oldest knockout competition.
Third-tier struggler Oldham stunned Liverpool with a 3-2 win.
"You have to take it on the chin, but there has been plenty of warnings throughout the weekend," Liverpool manager Brendan Rodgers said. "If your application is not right, you can get found out."
Liverpool fielded a weakened lineup but still contained a raft of internationals and millionaire players, who didn't appear to be up for the fight until it was too late.
"I am left speechless by the result," said Oldham striker Matt Smith, who scored twice for a team that is 55 places lower than Liverpool in English football's rankings. "We went out there wanting to battle together."
Oldham made its name in the early 1990s when the club reached two FA Cup semifinals (1990 and '94) and a League Cup final ('90), where it lost to Nottingham Forest.
The team managed by former Manchester City striker Paul Dickov revived those memories by going ahead through Smith in the third minute, then taking a 3-1 lead after Luis Suarez - who captained Liverpool for the game with Steven Gerrard on the bench - equalized.
Joe Allen's deflected goal in the 80th set up a tense closing stage but Oldham saw off a flurry of attacks to set up a fifth-round match with another Merseyside team - Everton.
"There are a lot of emotions at the minute," said Dickov, whose team has lost seven of its last eight matches. "I am very proud and I am very pleased for the fans as it has been a long time without success for them."