By Chris Harris

Arsène Wenger admits there is "no logical explanation" for Thomas Vermaelen's ongoing injury problem.

The Belgian defender has not played since September 7 when he completed a full 90 minutes for his country in a Euro 2012 qualifier against Turkey. He returned to England with an Achilles injury and was expected back in action with a week.

Nine weeks on, Vermaelen is still no closer to a first-team return after suffering a setback in training on Monday. At his pre-match press conference, Wenger explained why he is reluctant to put a timescale on the centre back's recovery.

"I don’t know his next stage - he has seen specialist after specialist and the scans are OK," explained Wenger.

"We have to be patient. We know a lot medically nowadays but there are some mysteries that we do not know about.

"At the moment we have no rational explanation for his pain. That means there is no reason to have surgery and there is no logical explanation for his pain. We have to be patient and just hope it will go.

"That means rest at the moment."

Copyright 2014 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source 12 Nov 2010