Mikel Arteta has admitted Bukayo Saka still has "a lot of things to go through" before he is ready to play again, on the eve of Arsenal's Champions League clash against Athletic Bilbao.
Arteta has been boosted by the return of William Saliba after the France international hobbled off in the opening exchanges of the Gunners' defeat against Liverpool prior to the international break.
However, captain Martin Odegaard will miss the match in Spain after he fell awkwardly on his right shoulder in Arsenal's win over Nottingham Forest at the Emirates on Saturday, while Saka, who sustained a hamstring injury on August 23, remains sidelined.
Kai Havertz is another absentee and Ben White, who has not played since his side's opening-day win at Manchester United, has not travelled either.
Arsenal will host Pep Guardiola's Manchester City on Sunday as they bid to keep the pressure on rivals' Liverpool who have won all four of their Premier League fixtures so far.
Noni Madueke impressed against Forest and could deputise for Saka once more on Tuesday.
But, when asked for a timeline on Saka's return, Arteta - who said at the end of last month that the England forward should only be sidelined for a "couple of weeks" - replied: "He still has quite a lot of things to go through, and it is very early to understand what week he is going to be available.
"He will certainly be pushing to be available as quickly as possible. Unfortunately we have a few players already out and that means we are limited in certain positions."
Arsenal begin their bid to win the Champions League for the first time in their history at the San Mames Stadium with an opening rubber against Athletic Bilbao - who are back in Europe's top-tier competition for the first time in a decade.
The Gunners saw off Real Madrid in the quarter-finals last season before they fell at the last-four stage to eventual winners' Paris St Germain following one-goal defeats in both legs.
But Arteta, who is without a trophy as Arsenal manager since he oversaw his side's 2020 FA Cup triumph, said: "We were very unlucky in the semi-final not to get through.
"That is the moment you get deflated. And you have to understand what you need to do. But you take a lot of learnings from that, it is painful, and the expectations that we created was that we could go all the way.
We showed a very good level of consistency and quality to reach that.
"It show how difficult it is because we haven't won it (the Champions League) yet. We know it is going to be a really long journey.
"The margins in this competition are super small and you have to give yourself the best chance to win the game, and that includes having a full squad. But we are good enough and we can compete with any opposition on the day."
Watch Liverpool v Atletico Madrid in the Champions League on Wednesday from 7.30pm on RTÉ2 and RTÉ Player. Follow a live blog on rte.ie/sport and the RTÉ News app
Watch Newcastle United v Barcelona in the Champions League on Thursday from 7.30pm on RTÉ2 and RTÉ Player. Follow a live blog on rte.ie/sport and the RTÉ News app
