Arsene Wenger's absentees for the away tie include Andrey Arshavin (hamstring), William Gallas (back), Eduardo (hamstring), Alex Song (knee) and goalkeeper Manuel Almunia (finger).
Arsenal's injury crisis could see veteran former England defender Sol Campbell starting in defence, while Lukas Fabianski is expected to deputise in goal.
Thomas Vermaelen is set to shrug off heavy bruising sustained against Manchester United and start at the back.
Porto may be missing Ruben Micael (shoulder), but Portugal international Raul Meireles and Brazilian striker Hulk are tipped to start.
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Source: DSG
