Sokratis Suffers Apparent Leg Injury in FA Cup Clash vs. Manchester United

Sokratis Papastathopoulos left Arsenal's FA Cup fourth-round tie against Manchester United on Friday after just 20 minutes with what looked like a leg injury.

The centre-back went down after contesting a ball in the air with United forward Jesse Lingard. Sokratis' pained expressions told a grim story for a suspect Arsenal defence already thinned by injuries:

Sokratis was replaced by Shkodran Mustafi. Not everybody was pleased to see Mustafi enter the fray:

United soon exposed the Gunners' back line with goals from former Arsenal star Alexis Sanchez and Lingard. Those goals underlined Sokratis' importance:

While Mustafi has been mistake-prone at times this season, Sokratis' experience and no-nonsense approach have proved valuable. The 30-year-old, signed from Bundesliga side Borussia Dortmund in the summer, has added some of the aggression and aerial power Arsenal have lacked at the back for too long.

Some Gunners defenders, including Mustafi, can be guilty of trying to play their way out of trouble. By contrast, Sokratis is quicker and more decisive when taking defensive actions.

He isn't afraid to put his head in where it hurts, nor will he hesitate to put his laces through the ball and sky a clearance instead of risking a forward pass. It doesn't always make for the prettiest of performances, but Sokratis has been effective even though Arsenal continues to struggle in defence.

The Gunners have conceded 32 goals in 23 matches in the Premier League. Things are unlikely to improve with Sokratis on the treatment table.

Rob Holding is already out for the season, leaving the inconsistent Mustafi to partner Laurent Koscielny. The latter is still capable but is also 33 and coming off an absence of six months with a ruptured Achilles.

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Hector Bellerin will also miss the rest of the campaign with a ruptured ACL.

Adding Sokratis to the list of casualties would mean Arsenal head coach Unai Emery has little choice but to try to acquire reinforcements during the remainder of the January transfer window.