Brighton & Hove Albion head coach Roberto De Zerbi has confirmed that Pascal Gross will miss Wednesday's trip to Chelsea in the EFL Cup third round.
The 32-year-old midfielder was forced to miss Brighton's 3-1 home win over Bournemouth in the Premier League last weekend due to a muscle injury.
Summer signing James Milner was also absent with a similar injury and the duo will not be available for selection when Brighton travel to Stamford Bridge on Wednesday.
De Zerbi has also revealed that striker Evan Ferguson is doubtful and will be assessed ahead of kickoff as he is yet to have fully recovered from a knee problem sustained before the international break.
The 18-year-old came on for the final five minutes of Brighton's 3-1 away win over Manchester United before playing just the first 45 minutes against Bournemouth.
Providing an injury update on his Brighton squad ahead of Wednesday's clash with Chelsea, De Zerbi said: "Pascal [Gross] and James Milner will miss this one.
"I have not decided about Evan [Ferguson] yet, I would like him to play at his best. He wasn't in his best physical condition on Sunday but he wanted to play.
"We need the best condition of the players if we want to compete every three days. We have to change the 11 and take the best decisions game-by-game."
In the absence of Gross and Milner, De Zerbi could hand a start to former Chelsea man Billy Gilmour, who is set to battle with summer signings Carlos Baleba and Mahmoud Dahoud for a place in the first XI.
Gilmour, who has started five of his seven appearances for Brighton so far this season, was named Man of the Match after the Seagulls' win over Bournemouth and is in contention to face the West Londoners for the first time since leaving the club in September last year.
"We will see if Billy can play [from the start]," said De Zerbi. "He has become an important player, but I have no doubt that we have to [select] some of the new midfielders – Dahoud and Baleba.
"Dahoud I think is improving. He can be another important player for us, but we have to give him time, to understand our play, our idea. It's not so easy, especially for midfielders and centre-backs, they need time."
Discussing his team selection further, the Italian added: "Tomorrow, the best team [will play]. Obviously I have to [take into consideration] the players who are at risk of injury.
"Maybe the players who can't play 90 minutes, the players who played 90 minutes against Bournemouth, maybe they cannot play another 90 minutes (against Chelsea), and I have to consider another game on Saturday (against Aston Villa). But for tomorrow, the best team I can choose."
Brighton, who are looking to reach the EFL Cup fourth round for the fourth successive season, beat Chelsea both home and away in the Premier League last season, including a 2-1 victory at Stamford Bridge in April, before losing 4-1 to the Blues in a pre-season friendly during the summer.
