Chelsea manager Mauricio Pochettino on Friday admitted the ankle injury that will rule out new signing Romeo Lavia for several weeks is a "sad situation" for his spluttering side.
Pochettino is waiting to discover exactly how long he will be without Lavia after the Belgium midfielder twisted his ankle in training last week.
It is feared the 19-year-old could be sidelined for at least six weeks, further upsetting Pochettino's attempts to spark Chelsea into life after a troubled start to his reign.
One of a host of big-money Chelsea signings since Pochettino took charge in the close-season, Lavia is yet to make his debut following his £58 million ($71 million) move from Southampton.
"We are really disappointed because he was training really well last week," Pochettino told reporters on Friday.
"He's twisted his ankle and now we wait for Monday to hear from the doctor.
"We hope it's not a big issue. It's (a) real shame. It's a sad situation because he was nearly fit to be involved again with the team. We need to assess him."
Lavia is not Pochettino's only absentee and Chelsea will again be without injured trio Reece James, Armando Broja and Benoit Badiashile against Bournemouth on Sunday.
"It is very short, the squad. We are going to face Bournemouth with 14 or 15 players. Now it is important to recover players to be more competitive," Pochettino said.
Chelsea earned just four points from their first four Premier League games this term and sit a disappointing 12th in the table.
Defeat at home by Nottingham Forest before the international break underlined the size of the task facing Pochettino as the former Paris Saint-Germain boss rebuilds the Blues.
"We cannot concede this type of goal we conceded against Nottingham. We cannot be so weak, we need to be more solid. We have players with experience, players that can do better," Pochettino said.
"In the end we need to be more competitive. I say that because I don't want to use another word. We need to be more naughty, more aggressive.
"To increase our level is not about our quality, it's to compete. To compete more in every single moment. Because we're still building the team, finding this balance. It's a matter of time.
"For sure we will be in European competition next season. We need to believe in the quality."
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