Barcelona striker Lionel Messi is set to miss his sides crucial Group F UEFA Champions League clash with Inter Milan on Tuesday and is a major doubt for next Sunday’s ‘El Clasico’.

Messi was substituted 14 minutes from time during La Blaugrana’s 1-1 draw away to Athletic Bilbao on Saturday night and Barcelona fans will be sweating on the Argentine’s fitness going into a crunch week for the Spanish and European champions.

'La Pulga' picked up an injury to the abductor muscle in his left leg and has already been ruled out of the crucial UEFA Champions League clash with Inter Milan on Tuesday.

It is now thought that the 2009 FIFA World Player of The Year favourite will also miss Sunday’s mouth-watering ‘El Clasico’ with table-toppers Real Madrid.

Barca coach Pep Guardiola confirmed to the official Barcelona website that ‘the early signs are not good’, and with Eric Abidal, Rafael Marquez and Yaya Toure stricken with Swine Flu, in addition to new summer signing Zlatan Ibrahimovic also struggling, the Catalans face a mini-injury crisis heading into a mammoth week.