Thomas Tuchel has confirmed that Chelsea duo N'Golo Kante and Thiago Silva have tested positive for Covid-19.
The pair were notably dropped from Chelsea's squad to play Tottenham in the first leg of their Carabao Cup semi-final against Tottenham.
But Tuchel explained in a pre-match interview with Sky Sports that Kante and Silva have coronavirus and are now isolating.
Reports surfaced prior to the match on Wednesday that Chelsea were dealing with a number of new Covid-19 cases.
Spurs boss Antonio Conte also revealed in a press conference this week that they were checking on a number of possible positive results in their own camp.
Tottenham had to deal with a major Covid-19 outbreak before Christmas, seeing a number of Premier League games postponed and ultimately seeing them kicked out of the Europa Conference League.
Meanwhile, Romelu Lukaku has been reinstated to the Chelsea starting lineup. The striker was dropped for the Blues' 2-2 draw with Liverpool following the release of an unauthorised interview with Italian media last week.
Elsewhere for the Blues, Kepa Arrizabalaga has come in for the AFCON-bound Edouard Mendy, while Malang Sarr starts at centre-back.
Spurs are without Eric Dier, who has emerged as a key figure under Conte, and Matt Doherty gets a rare start at left-wing-back.