Jurgen Klopp was left holding a fake contract signed by iShowSpeed after Liverpool's FA Cup exit last month.
In March, Manchester United defeated Liverpool in an FA Cup classic which saw the Red Devils emerge 4-3 winners after extra-time.
When Klopp went into the Old Trafford press room to do his press conference, there was a fake contract on the desk, which it appears was left over from a PR gag.
IShowSpeed signed a 'contract' with the club in a video posted to social media, in which the social media star is told 'Welcome to Old Trafford' and presented with the deal - leaving Speed in disbelief.
Quoting that clip, radio journalist Gaz Drinkwater wrote on X (formerly Twitter): 'Another funny thing about this. United left the fake ‘contract’ on the table after. Guess who was the next person sat there' - attaching a picture of Klopp with the document.
Klopp was understandably confused by the item on the desk, moments after their FA Cup exit at the hands of Manchester United.
In the video on social media, Speed joked that he should write his full name - Darren Jason Watkins Jr - and asked how much he was getting paid.
He caused mayhem whilst attending Manchester City's Champions League exit to Real Madrid on Wednesday night, by riling up the home fans.
Afterwards, he met Antonio Rudiger after the German defender scored the decisive penalty in Real Madrid's progression to the semi-finals.
Liverpool's trophy hopes have dwindled significantly since their FA Cup exit at the hands of Man United.
They have lost ground in the title race following last weekend's 1-0 defeat to Crystal Palace, and were eliminated from the Europa League by Atalanta.
Liverpool sit third in the league table, two points behind leaders Manchester City, ahead of their game against Fulham on Sunday.
In his pre-match press conference, Klopp was defiant in their chances to win the Premier League, and was sure that Liverpool would bounce back despite a disappointing week on the field.
Amad Diallo was the 121st-minute hero to secure the Red Devils progression in the FA Cup at the expense of Klopp's Reds.
Manchester United's reward for beating Liverpool last month is an FA Cup semi-final against Coventry City, which is also being played on Sunday afternoon.