Arsenal goalkeeper Petr Cech could be absent for as long as three weeks due to a hamstring injury, according to manager Unai Emery.
The 36-year-old was replaced just before the break during the 2-0 Premier League win over Watford and replaced by English top flight debutant Bernd Leno .
Cech has remained Arsenal's number one despite the arrival of Leno from Bayer Leverkusen but is now set for an enforced spell out of the first team.
"I don’t know [when Cech will return now," he told the media . We will look tomorrow.
"I hope not more than maybe two or three weeks he can stay with this injury. It’s muscular. I think yes [it is hamstring problem]."
The former Czech Republic international is in line to miss two games due to the injury.
Then the Gunners are not in action again until they host Leicester City at the Emirates Stadium on October 22, so if Emery's three-week prognosis proves to be accurate Cech could resume the campaign against Claude Puel's men.
With or without Cech, the Arsenal boss will be hoping for an improvement in performance after his side rode their luck before securing a late win over Watford.
Troy Deeney and Andre Gray both passed up presentable opportunities for The Hornets before Craig Cathcart's own goal gave the hosts the lead.
Mezut Ozil completed the victory with seven minutes left to send Arsenal fifth and leave Emery content with a seventh win in a row in all competitions.
"We need more control, we need to continue to improve with the control, with the possession, with the positioning," the Spaniard explained.
"But it’s not easy. Each match is very difficult in the Premier League.
"I'm happy because I think we are becoming more competitive.
"This way is good to continue improving on other things, like playing well with control and our quality."