Cesc Fabregas's monumental contributionto Arsenal's first-leg comeback at the Emirates last week went beyond playing with a cracked fibula and scoring the equalisingpenalty he also helped ensure that two of Barcelona'smost important players will sit out tonight's match.
Central defenders Carles Puyol and Gerard Pique were sent off and booked respectively for fouls on the Arsenal captain in the 2-2 draw and both are suspended for the quarter-final second leg.
The heart has been ripped out of Barcelona's defence and manager Pep Guardiola must pick two from three replacements, each carrying an element of risk.
Argentinian Gabi Milito is thesurest to start but he is only three months back from a knee injury that ruled him out for a year and a half.
Rafael Marquez should line up alongside him, given his wealth of experience in the role, but the Mexico captain has looked shaky all season.
If the fans had their way, Yaya Toure would partner Milito, but he has not played in central defence since last season's ChampionsLeague final victory againstManchester United.
Whoever steps in, they have big boots to fill with Pique and Puyol marshalling La Liga's meanest defence, concedingonly 19 goals.
And a large proportionof Barcelona's attacks begin with one of them bringing the ball out from the back.
Milito's return from injury has felt like anew signing, withgoalkeeper VictorValdes saying: 'It is not just his contribution on the pitch.
Versatile: Yaya Toure
'He also plays a big part in the dressing room.'
Milito has started five of Barca's last nine games but alongside him could be a player who has played 17 minutes in that time.
Marquez's trademark crossfield passes are still finding their target but defensively he has looked a liability, and the decision tohand the 31-year-old a new contractthis season looked more like a thank-you gift than good forward planning.
If Guardiola finally decides against Marquez, Toure will play alongside Milito.
The man once rejected by Arsene Wenger after a trial against Barnet was a revelationlast season when he filled in with such distinction against Chelsea and Manchester United in the Champions League and against Athletic Bilbao in the Spanish Cup final.
But since that Champions League final in Rome, when he shut out Cristiano Ronaldo, the Ivory Coast star has not played a single match as a centre back.
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