Borussia Dortmund midfielder Henrikh Mkhitaryan faces a spell of four weeks on the sidelines are picking up an ankle injury in Saturday's 2-0 defeat to Mainz.

The 25-year old replaced Shinji Kagawa mid-way through the second half, and picked up the injury in the closing stages when he was involved in a collision. It is believed to be when he struck the bar was a strong shot in the final minute, but clipped someone's boot in the process.

The club today confirmed that the Armenian will be sidelines for four weeks, which means the midfielder could miss up to six games, which include - two UEFA Champions League fixtures and next weeks Revierderby against Schalke 04.

Jurgen Klopp's injury crisis is already bad, with Marco Reus, Jakub Błaszczykowski, İlkay GündoğanJi-Dong Won, Nuri Şahin and Oliver Kirch already receiving treatment.

Mkhitaryan arrived to Dortmund from Shakhtar Donetsk in 2013, and has since gone on to score 13 goals in this debut season last term.