Arsenal manager Mikel Arteta is still in the dark about Bukayo Saka's condition following his enforced withdrawal in their 1-0 North London derby win over Tottenham Hotspur.
The 23-year-old was once again instrumental to the Gunners' victory over Ange Postecoglou's side, as it was his corner that Gabriel Magalhaes nodded home in the second half.
Saka has now provided an assist in each of his four Premier League appearances this season, but the England international went down towards the end of the match and could not complete the full 90.
Saka was seen shaking his head as he trudged off the pitch to be replaced by 17-year-old Ethan Nwaneri, who contributed to the late defensive effort as Arsenal saw out an incredibly hard-fought win.
Arteta was unsurprisingly asked about Saka's condition in his post-match press conference, but he admitted that he is none the wiser about his issue, only that it was severe enough to force him off the field.
Saka an early doubt for Atalanta BC, Man City ties?
"I don't know. I made two changes with the front players and suddenly he's down. I looked at the bench and the options that we had and we had to adapt. I don't know exactly what it is but he could not continue," football.london quotes Arteta as saying.
Arsenal were already without a surfeit of experienced first-teamers for Sunday's derby, with all of Martin Odegaard, Oleksandr Zinchenko, Riccardo Calafiori, Kieran Tierney, Takehiro Tomiyasu and Mikel Merino missing alongside the banned Declan Rice.
Nwaneri was one of five teenagers on the Arsenal bench as a result, joining Myles Lewis-Skelly, Ayden Heaven, Maldini Kacurri and Ismeal Kabia in the matchday squad, while Tottenham had both Dominic Solanke and Micky van de Ven back in their XI.
However, Arsenal defied their limited squad depth with a defensive masterclass in North London, where they also benefitted from Tottenham's wastefulness in the final third and spate of unsuccessful crosses.
With 10 points from their first 12 on offer, Arsenal are second in the rankings behind perfect Manchester City, whom they lock horns with next weekend in what is already a top-of-the-table clash.
Arteta admits to sleepless nights over injury crisis
Arteta admitted that he did not enjoy having to prepare for Sunday's derby, though, as the injuries to Calafiori, Odegaard and Zinchenko forced him to rejig his plans on numerous occasions.
"I didn't enjoy it because I didn't sleep much. I looked ahead to Spurs for four or five days and I had a super clear plan how to do it. I prepared all the meetings, the training sessions and everything," Arteta added.
"Then I get the news that we've lost a player, and then another player and then another player, and I had to completely change it and adapt the plan to the players that we had available. So, it was a great challenge."
Arsenal's victory marked their third in a row away from home against Tottenham, a feat that they had never previously managed in the Premier League era, while two of their defenders also emulated a Tony Adams achievement.
Before next weekend's daunting trip to the Etihad, Arsenal begin their Champions League campaign away to Europa League holders Atalanta BC on Thursday evening.
