Jurgen Klopp will miss Liverpool's Premier League match against Chelsea on Sunday, the second time the manager has been forced out since joining in 2015.
A positive test will cause Klopp to miss the Stamford Bridge tour, and as a precaution, the 54-year-old is believed to have COVID-19.
As a result, he could also miss the first leg of the League Cup quarter-final against Arsenal on Thursday night, which will be Liverpool's fifth first-team game without Klopp during his more than six-year reign.
But Klopp also missed a game on medication grounds, just four months after taking over Anfield.
He had spoken to reporters as part of his pre-match press conference when he was ill and needed emergency appendix removal on December 6, 2016.
In Liverpool's match against Sunderland at Anfield, he was Klopp's then-deputy, Zeljo Bouquets, supported by Peter Kravitz, Peppyn Lijdez and John Actenberg.
It was sure to be an eventful afternoon, and in the 77th minute, a large number of fans drew 2-2 in protest against Fenway Sports Group's planned purchase of 1,000 season tickets, and the number of seats in the main stands increased from 59 to 77.
On the pitch, the Reds had just one change in their 2-0 defeat in Leicester, with Lucas Rewa coming on for Joe Allen.
Welshman and Dejan Lovren were forced to leave before half-time, which weakened Liverpool's advantage.
Things came alive after half-time, with Roberto Firmino scoring a goal and assisting another for Adam Lallana, while Sunderland goalkeeper Vito Mano has been busy with a series of saves.
But the departure of thousands of supporters seemed to suck away the momentum of the game, but the team took advantage of two late goals.
Adam Johnson scored first, Simon Mignolet made a mistake in the 89th minute before Mamadou Sacco allowed Germain Defoe to turn around and equalize.
Bouak is a composed figure on the sidelines, but the atmosphere clearly affects Liverpool, especially without their leader.
Two days later, Klopp announced he was "back in the game" and assessed the poor performances of 11 Premier League games in which his side had only won three times, lost five and drawn three, saying: "We have to keep going."
The subsequent 2-1 defeat to West Ham in the FA Cup replay and the subsequent 6-0 win over Aston Villa on Valentine's Day kicked off the season.
Klopp's trip to Chelsea has been very different, and this time he will most likely pass on his message at home to Lijadez.
Either way, Liverpool are hoping for a more positive outcome than the 2-2 draw with Sunderland six years ago.
Liverpool 2-2 Sunderland
Anfield
February 6, 2016
Target: Firmino 59 'Lallana 70'; Johnson 82 ', Defoe 89'
Liverpool: Mignolet; Klein, Toure 12', Sarko, Moreno; Lucas 86', Jen; Milner, Lallana, Arun (Ibe 45 + 2'); Firmino
Substitutes: Ward, Flanagan, Benteke, Sturridge