La Liga leaders Barca left short at the back with Vermaelen ruled out for a month

Thomas Vermaelen will be out a month after tearing a calf muscle, FC Barcelona said Monday, leaving the Spanish champions with just two fit centre-backs.

The Belgian was substituted after sustaining the injury during Barca's 5-0 win at Levante on Sunday, which sent them three points clear at the top of La Liga.

"Tests carried out on the defender show that he has torn a muscle in his right calf and will be out for around four weeks," Barcelona said in a statement.

With Samuel Umtiti taking treatment on a knee cartilage problem in Qatar, it leaves Barcelona with only Gerard Pique and Clement Lenglet able to play in the heart of their defence.