Mauricio Pochettino confirmed on Monday that newly-signed striker Christopher Nkunku did not sustain a serious injury but will be absent from Tuesday's crucial Carabao Cup semi-final second-leg clash against Middlesbrough.
The Blues are gearing up for what is arguably their most crucial match of the season so far, aiming to secure a spot in the Carabao Cup final after a 1-0 defeat in the first leg at the Riverside Stadium two weeks ago.
Chelsea will be without 10 first-team players on Tuesday but are still anticipated to prevail against a Boro side currently positioned 11th in the Championship.
Nkunku, who experienced an injury that delayed his debut until December, had hoped to overcome a hip injury to be eligible but will once again be an onlooker from the sidelines. Pochettino informed reporters, "No, [Nkunku] is not available for tomorrow."
"It is a shame but he is still recovering from some suffering in his hip and we hope he can be back as soon as possible with the team - it's not a big issue," the Argentine said.
"Malo Gusto is out tomorrow. He suffered an injury against Fulham and is not available for tomorrow."
Chelsea have brought back midfielder Cesare Casadei from Leicester City and winger Diego Moreira from Lyon. Casadei is ineligible for both the Carabao Cup and FA Cup due to being cup-tied, but Moreira is available.
"We need to assess them both now after they came back from their loan," Pochettino explained.
"They have good potential and they are going to be part of our squad and we will make the decision whether they will be part of the squad or team every week. It is good news because we suffer a lot of injuries so it is good for us."
A victory over Middlesbrough could alleviate the pressure on Pochettino and his young squad, setting up a cup final against either Liverpool or Fulham at Wembley Stadium in February.