Chelsea duo Romelu Lukaku and Timo Werner are set to miss their side's next two Premier League games after picking up injuries in the midweek Champions League win over Malmo, manager Thomas Tuchel confirmed on Friday.
Both forwards hobbled off in the first half against the Swedish side, with Lukaku's ankle injury looking particularly bad after he stayed down for as long as four minutes.
"They are out tomorrow and probably the Southampton game and then we will see. What I can tell you for sure is they are both in treatment, positive and not worried but out of the next two games for sure," said Tuchel ahead of Saturday's Premier League game against Norwich City.
Midfielder Christian Pulisic will also be unavailable as he continues to recover from an ankle problem.
Tuchel defended the decision to play Lukaku against Malmo despite the Belgian's already heavy involvement in the season.
"It was a perfect role for Romelu to take responsibility. Mentally, he is a bit overplayed but that does not mean we have to rest him. Jorginho and Mason Mount are in the same spot. It is like this, they have played a lot of competitions," he said.
The German added that he did not regret letting go of the likes of Tammy Abraham, Olivier Giroud and Michy Batshuayi in the close season, saying that he had enough attacking players to make up for Lukaku's absence.
"Football does not work like this, you cannot keep a squad of 40 players. Do you think Tammy, Oli and Michy would be in perfect shape now? It's a lot of bad luck that we have two injured players in the same position," he said.
"If we don't have Romelu the game will be different but we have the same power, the same people in the same spaces when we finish our attacks."
Chelsea sit top of the standings with 19 points from eight games, while opponents Norwich are winless and in 20th place.
Norwich boss Daniel Farke said Saturday's clash wasn't a "season-defining" one but a result could give them a huge boost.
"Chelsea away is probably the toughest task in world football. The odds are against us but there is never a 100% guarantee on the outcome," he said.
