Arsenal face the daunting challenge of seeing off Barcelona at their Camp Nou home following last week's Champions League quarter-final first leg 2-2 epic at the Emirates Stadium.
The Spanish giants cruised into a two-goal lead thanks to the impressive Zlatan Ibrahimovic but, following Theo Walcott's introduction, the Gunners stormed back into the contest.
He halved the deficit before Cesc Fabregas was brought down by Carles Puyol in the penalty area.
The central defender was dismissed for his part in the incident and Fabregas stepped up to blast home, but his effort came at a cost.
He suffered a small fracture in his right fibula and will miss the rest of the domestic season.
Aaron Ramsey (broken leg), Kieran Gibbs (broken metatarsal), Robin van Persie (ankle) and Johan Djourou (knee) all remain out.
William Gallas, Andrey Arshavin and Alex Song will also miss the clash through calf injuries after being forced out of the first leg but Arsene Wenger's men will be looking to exploit Barca's defensive problems.
Puyol will miss out after his dismissal in London and fellow centre-half Gerard Pique picked up his third caution of the competition, also ruling him out through suspension.
But with Lionel Messi, Xavi, Thierry Henry, Daniel Alves and Pedro all to call upon, the Catalans have world-class stars in abundance and the La Liga holders are overwhelming sportsbook favourites to win the contest and seal their place in the last-four.
Elsewhere, Jose Mourinho and his Internazionale side will be striving to defend a narrow 1-0 first leg lead over CSKA Moscow as they make a long journey to the capital of Russia.
Argentina striker Diego Milito scored the only goal of the game at San Siro and the Nerazzuri will be hoping their inability to turn first leg chances into goals won't come back to haunt them.
They have a number of potential match-winners in their ranks with Samuel Eto'o, Wesley Sneijder and Goran Pandev likely to feature prominently but, with Mourinho and striker Mario Balotelli settling their much publicised off-field spat, the livewire frontman may also come into contention.
CSKA must look to Alan Dzagoyev, Milos Krasic and Tomas Necid if they are to force their away back into the contest and prolong their unlikely European title-challenge.