On Tuesday, April 15, Sky Sports confirmed that Ilkay Gundogan had signed a new deal at Borussia Dortmund but will miss the rest of the season and the 2014 FIFA World Cup.
Later that same evening, Aaron Ramsey made his long-awaited Premier League return against West Ham—coincidentally returning against the same team he hurt his groin against on Boxing Day earlier in the campaign.
These were two injuries which severely derailed Arsenal and Borussia Dortmund's seasons, but they're not the only ones. We've picked out 18-20 ailments that have threatened entire teams' seasons as we build up to the World Cup.
All statistics are from WhoScored.com. All selections are from the 2013-14 season only.