Arsenal manager Mikel Arteta says the injury suffered by defender Riccardo Calafiori during the 1-0 win against Shakhtar Donetsk is "a bit of a worry".

The Italian, who joined from Bologna in a summer deal worth up to £42m, went off in the second half of Tuesday's Champions League game after seemingly twisting his right knee.

Arsenal are already without key attacking players Martin Odegaard and Bukayo Saka, while defender Jurrien Timber is also injured.

"He felt something, he could not continue playing," Arteta said of Calafiori.

"It is a bit of a worry."

The Gunners, who are third in the Premier League table, face league leaders Liverpool at Emirates Stadium on Sunday.

Oleksandr Zinchenko was on the bench and appears an obvious replacement if needed at the weekend - although Arteta instead sent on youngster Myles Lewis-Skelly for Calafiori against Shakhtar.

Former Chelsea forward Chris Sutton says Calafiori will be badly missed if he cannot feature against Arne Slot's Liverpool side.

Sutton told BBC Radio 5 Live: "It's such an intense period.

"Injuries put pressure on the squad. Arsenal are missing key players such as Bukayo Saka and Martin Odegaard.

"It was the way Riccardo Calafiori fell. When he went down again, you think there's something there. It is so unfortunate as he's been brilliant since he came to Arsenal. He can play in the midfield role, he has the awareness for that.

"Calafiori will be a massive loss at the weekend. Arsenal need to find a way of muddling their way through."

Arsenal are in the midst of a run of seven matches in 23 days in all competitions, with many players previously playing for their countries during the international break.

A damaging defeat to Bournemouth at the weekend was followed up by a less than sparkling showing against Shakhtar - but Arteta is confident his side will be at their best on Sunday.

He said: "We played two and a half days ago, with guys coming from internationals after flying from Brazil and many countries.

"I was expecting that we could drop off a little bit. Now we have four days, and believe me on Sunday we will be flying."

Former Arsenal defender Matthew Upson said Arteta's side must deliver consistent all-round performances.

He told BBC Radio 5 Live: "David Raya and his defence answered the questions and stayed really solid.

"But that's going to wear thin eventually. Arsenal fans will be thinking their team will need to step it up to keep up with Liverpool and Manchester City.

"There's holes in that performance and quite a lot of questions they'll have to answer."