By Arsenal correspondent Tony Hughes

Laurent Koscielny took part in Arsenal’s final training session on Tuesday ahead of their must-win Champions League showdown against Barcelona.

Long-term absentee Mikel Arteta also trained at the Gunners’ London Colney training headquarters as the squad were put through their final paces before flying to Spain on Tuesday afternoon.

It is a double boost for Arsenal as they bid to overturn the form book and Champions League history by overturning a 2-0 deficit in the away leg of a last-16 tie.

Koscielny, who is widely regarded as the Gunners’ outstanding centre-back, has been sorely missed in the four matches he has been absent with a calf injury.

Per Mertesacker and Gabriel were troubled by Watford front pair Odion Ighalo and Troy Deeny as Arsene Wenger’s team lost 2-1 on Sunday and crashed out of the FA Cup.

Club captain Arteta has barely played this season due to a chronic calf condition but his experience as a substitute could offer a useful alternative to Wenger in Wednesday’s showdown at Camp Nou.

The possible return of the experienced pair will much-needed options to Arsene Wenger, who is unable to call upon midfielders Aaron Ramsey, Alex Oxlade-Chamberlain, Santi Cazorla, Jack Wilshere and Tomas Rosicky.

The latest Arsenal injury news is that Ramsey is expected to be out for at least a month with a thigh injury sustained at Hull last week.