David Luiz has suffered a fresh setback at Chelsea.

Chelsea boss Antonio Conte has revealed that Luiz's injury is worse than feared.

He has been missing from first team action for three weeks, but was expected to be fit for Chelsea's clash with Southampton on Saturday.

However, Conte has said that Luiz, 30, isn't ready to start and could be out for longer than expected.

"David has a big inflammation in his knee," Conte told reporters in a press conference on Friday.

"We are trying and trying to solve this situation with the doctor. It's important to assess the situation day by day and try to try to sort this problem.

"I don't know when he's able to come back with us. With the doctor and the medical department we are try to solve this situation.

"The player is working apart [from the group]. He worked in the pool, I saw him [on Friday] running on the pitch but very slowly.

"This is a serious problem but we hope to solve this problem soon."

The Italian also divulged that Luiz was frustrated to be out.

Conte continued: "I think every player is frustrated when they don't play, especially when they have an injury.

"For sure there is a lot of frustration for the injury because every player likes to train and try to put the coach in difficulty with their selections.

"I understand because I was a player and when I was injured my feeling was very bad."