Oleksandr Zinchenko will undergo a scan on his calf on New Year's Day to determine the extent of his injury.
The Ukraine international, 27, missed Arsenal's 2-1 defeat against Fulham at Craven Cottage on New Year's Eve due to the problem. Arsenal's social media team described his injury as a "slight calf issue" before the game, but it could turn out to be quite serious.
The Gunners, who have dropped to fourth in the Premier League table after picking up just one point from their last three games, missed Zinchenko dearly in their most recent loss. The left-back's replacement Jakub Kiwior was hooked by Mikel Arteta at half-time.
The Arsenal boss was asked for an update on Zinchenko's fitness after the Craven Cottage clash. Arteta replied: "We don’t know. He felt something in his calf. We will scan him tomorrow and see how far he’s going to miss games."
Arteta needs Zinchenko fit due to a lack of options at left-back. Kieran Tierney was allowed to join Real Sociedad on a season-long loan in August, while summer signing Jurrien Timber ruptured an anterior cruciate ligament on his Premier League debut.
Mikel Arteta's dream Arsenal line up as last-gasp January transfers are securedKiwior was given the nod ahead of Takehiro Tomiyasu for the Fulham clash because the latter had only just returned from a calf injury. Tomiyasu, who will now head off to the Asian Cup to play for Japan, was Kiwior's replacement at the interval.
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Zinchenko also provides plenty of experience. The four-time Premier League winner knows what it takes to win silverware following his successful spell at Manchester City. He also won four League Cups, the FA Cup and the Community Shield under Pep Guardiola.
Arsenal are enduring their toughest period of the season and must get back to winning ways as soon as possible if they want to keep their dream of winning a first league title in 20 years alive. They aren't back in Premier League action until January 20.
Arsenal's final game before the winter break is in seven days' time when Liverpool travel to the Emirates for their third-round FA Cup clash. Arteta and Liverpool boss Jurgen Klopp are expected to rotate their squads after the busy Christmas period.
Arteta admitted: "We need to improve. We need to win games and in order to do that we need to win games. In order to do that we need to do it with players that after 20 League games, we have the chance to be the best in the League with these players."