Ander Herrera will be out for “weeks” with a fractured rib in what represents yet another serious blow to Louis van Gaal as the Manchester United manager attempts to deal with one of the club’s biggest injury crises of recent seasons.

Herrera was taken off with what was suspected as a back injury in the 74th minute of United’s 2-1 win over West Ham United on Saturday at Old Trafford. The midfielder took to Facebook that evening to write: “Three very important points! I hope my back is fine soon. Thanks for your messages!”

However, as reported by the Guardian the club was forced to delay an update on Monday evening it planned for the club website regarding his injury as more time was required to determine its seriousness, with the problem turning out to be a fractured rib.

A statement from United said: “Manchester United midfielder Ander Herrera sustained a fractured rib during the match against West Ham United on Saturday. The Spaniard was substituted in the 74th minute and the club will continue to monitor his progress over the next few weeks.”

United host Everton on Sunday before the international break with West Bromwich Albion and Chelsea the other opponents in October.

United have said he will be out for “weeks”, so whether Herrera will feature in any games next month remains to be seen.

With James Wilson, one of Van Gaal’s first-team strikers becoming an 10th injured player and Wayne Rooney suspended for three matches following his red card against West Ham, the manager has a particularly depleted squad.