Mikel Arteta has not ruled out returning to the transfer market as he expects Arsenal to be without Jurrien Timber for the season after the summer signing suffered a knee injury against Nottingham Forest.

It was confirmed earlier in the week that Dutch defender Timber will go under the knife after tests showed ligament damage – with Arteta also insisting the number of serious injuries suffered so early into the campaign is a “big worry” for player welfare.

Timber limped out of Saturday’s 2-1 Premier League win over Forest on Saturday, with the club confirming on Wednesday he suffered ligament damage.

The PA news agency understands Timber felt no immediate pain after a challenge with Brennan Johnson just before half-time and underwent stringent tests during the interval.

Club medical staff believe the outcome of the injury would not have changed had he been substituted immediately instead of playing on for five minutes of the second half before being replaced by Takehiro Tomiyasu.

Asked about Timber’s situation, Arteta said: “Huge blow. Especially for him after just joining the club. To have the injury he has is a huge blow.

“It is for the team because we recruited him with clear intentions and what he was bringing to the team was evident and he’s not going to be able to do it this season for us. We have to adapt. These things happen unfortunately and we have to move on.

“He’s been very good to be honest. He’s a special character. He knows, he’s starting to realise the extent of the injury and the amount of time he’s going to be out. But he’s in a good place. We are willing to help him obviously and be close to him, but we know it’s going to be a long journey.”

Kieran Tierney appeared set to depart the Emirates Stadium this season but, with Timber now sidelined and Oleksandr Zinchenko struggling for fitness, the Scotland left-back could now be retained.

Arteta, too, suggested Arsenal could dip their toe back into the market following the injury setback.

“We didn’t plan with this injury. We have to assess what the options are, what are the best players that we have because, as I said, my challenge is to get the best from the players that we have. I cannot assess anyone who is not here.

“We are always open and we have to be open as well to react if something happens, not only with an injury but if something happens in the market as well. That’s what we’re doing.”

Timber was not the only player to suffer serious injury in the opening weeks of the new season, with Manchester City’s Kevin De Bruyne and Tyrone Mings of Aston Villa also forced off.

Arteta also highlighted a number of other injury issues when asked if the problems could link back to the amount of football that players are being asked to complete.

“Also Emi Buendia, (Thibaut) Courtois, it happened to (Eder) Militao as well – there is something there,” he added.

“In the past you can say: ‘yes there have been games, there have been tours as well’. But with games, tours, the World Cup in January, plus this, plus that, plus internationals. It is a lot. It is too much for the players.

“It is incredibly demanding, when you see the next 36 months of the calender for these players it is just better not to look at it because it is incredible what they are going to be doing.

“We have to look after them but, as a club, when do you look after them? To prioritise other competitions? Then we are the ones that have to look after them – what we really need is to be sitting down (discussing plans), but I think it is too late, at least for the next 36 months it is too late already.

“I don’t know who needs to raise a voice here, but there are worries, big worries on that.”