Arsenal are facing an anxious wait to discover how much time summer signing Viktor Gyokeres will miss after suffering a muscle injury. The striker was ruled out of the Gunners' Champions League clash with Slavia Prague due to the problem and is set to undergo further tests to discover the severity of his injury. Gyokeres is also expected to sit out Saturday's Premier League clash with Sunderland at the Stadium of Light.Arsenal manager Mikel Arteta revealed his concern at losing Gyokeres to injury ahead of the Gunners' Champions League encounter. The Sweden international sustained the problem during Saturday's 2-0 Premier League win over Burnley at Turf Moor, leaving the Arsenal manager fearful that he may be out for an extended period of time. "I am concerned because he hasn't had many muscular issues and he needed to leave the pitch and he was feeling something," he told reporters. "That's obviously never a good sign, especially for a player that is very, very explosive. So we are digging in a little bit more to understand where we are in terms of the injury and we'll announce the moment we know."Gyokeres had opened the scoring in the match for Arsenal, before Declan Rice's goal sealed the win for the visitors, but was taken off at half-time after feeling some discomfort. The Gunners are hoping that the decision to substitute him after 45 minutes may have prevented the striker from suffering a more serious problem.Gyokeres will undergo further tests this week as Arsenal fear he may have suffered a hamstring injury, according to BBC Sport. The club's initial thinking is that he will be out for two weeks, meaning he will not play against Sunderland and will also be unavailable for international duty. New Sweden manager Graham Potter is set to name his squad for World Cup qualifiers against Switzerland and Slovenia but may well have to do without Gyokeres for the two upcoming fixtures. The striker's absence will be a blow for club and country. Gyokeres has six goals this season in all competitions for Arsenal following his big-money move from Sporting, while Sweden have endured a poor start to their World Cup qualifying campaign which has resulted in Jon Dahl Tomasson being sacked and replaced by Potter.Arsenal's first game after the international break is the small matter of a north London derby against Tottenham at the Emirates on November 23 and the hope is that Gyokeres will be fit for the crunch clash, per The Athletic. Gyokeres may not be the only injury victim set to return in time for the match against Thomas Frank's side. The Gunners are also hoping Noni Madueke, Kai Havertz and Martin Odegaard could be available to take on Spurs after injury in what would be a huge boost for Arteta.The Arsenal manager spoke about his injured players before his team's win over Burnley, saying: "I would say weeks, and some of them pretty soon, hopefully, if they keep evolving the way they are doing. Difficult to put a game - we have an international break, and after that, I think we'll have some back. I don't know if it's going to be all of them, some of them, but we'll be quite close by then."Arsenal have coped well without Gyokeres against Slavia Prague. Arteta's side cruised to a 3-0 win thanks to a Bukayo Saka penalty and two goals from Mikel Merino. The Gunners still have a perfect record in the Champions League this season ahead of their next fixture in the competition against Bundesliga champions Bayern Munich at the Emirates.Arteta's side are also now six points clear of nearest challengers Manchester City in the Premier League. Another victory against Sunderland on Saturday will see Arsenal head into the international break in great shape and buoyed by the possibility of welcoming some key players back to action once domestic competition resumes.