Arsenal are awaiting more information on Noni Madueke's injury, with the England star still awaiting a second scan on the knee injury he sustained against Manchester City.
The £48.5m summer signing was withdrawn at half-time during the draw with City and underwent a first scan on the problem last week. Arsenal have been hoping that he can avoid a lengthy lay-off but it had been suggested that he could be set to miss the next two months.
Madueke watched Arsenal's comeback win over Newcastle from home on Sunday as he continues his recovery, posting on instagram and hailing match-winner Gabriel a "monsterrrrr" following his last gasp strike that sealed all three points.
But Gunners boss Arteta admits the club remain in the dark over when ex-Chelsea winger Madueke be able to return to action.
"He hasn't had a [second] scan yet so he needs to wait a little bit more still with the brace and everything," said the Spaniard, ahead of Wednesday night's Champions League meeting with Olympiacos.
"So he's still in a stage where everything is super protective and once he comes out of that and has the scan we'll have more clarity about it."
Arteta's men face the Greek champions on the back of their victory at St James' Park, the manner of which has left the Spaniard very optimistic.
"That creates momentum and energy, and at the end we got what we deserved," he said.
"But it was done in a special manner, that now we need to use that momentum and energy to go tomorrow and play with the same quality, with the same intensity and effectiveness to beat Olympiacos."
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One player who didn't feature at Newcastle, despite travelling to the north east, was Ethan Nwaneri, with the 18 year-old left out of the matchday squad.
On his omission, Arteta said: "I talked to all the players and we had a meeting specifically about that and the scenarios that we're going to have throughout the season.
"Some of them are going to start, some of them are going to finish the game, some of them are going to be on the bench and won't be participating and some of them unfortunately are going to be out of the squad because with the Premier League you have the limitation with the numbers.
"Sometimes we have to travel with more players because things can happen, somebody can get ill or we have a doubt with somebody whether the next one is going to be available to play and unfortunately we have to do that.
"But the attitude of every player, because we have explained them and personally they know how we feel about it, has been really good and they will have the chances to play."
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