Arsenal left-back Sead Kolasinac has been ruled out for up to 10 weeks with a knee injury, but the club is hoping Aaron Ramsey will be back in training as soon as next week.
Kolasinac went off injured during Arsenal's 1-1 draw with Chelsea in Dublin on Wednesday, which the Gunners ultimately won on penalties, and the club said on Friday he will miss the opening two months of the season.
Arsenal said the defender "sustained an injury to his left knee. Will be out for 8-10 weeks."
The prognosis on Ramsey was more positive after he sat out the Chelsea game with a calf problem. The club said the Welshman "developed tightness in his right calf" and is continuing to be assessed, but he is "aiming to train next week."
Kolasinac's absence means Nacho Monreal is likely to be thrown straight into the starting lineup when the Gunners take on Manchester City next weekend in the opening round of the Premier League.
Monreal only joined up with the squad this week following the World Cup but could play his first preseason game against Lazio in Stockholm on Monday.
In transfer news, Arsenal have sold academy goalkeeper Joao Virginia to Everton for an undisclosed fee.
Virginia, 18, joined the Gunners from Benfica in 2015 but never featured for the first team. However, he is considered a promising talent who played for the club's under-23s and was also in Portugal's squad for the 2016 Olympics and this summer's U19 European championship.
"We would like to thank Joao for his contribution to the club and wish him well for the future," Arsenal said in a statement.