Cheer up, Messi... Barca may be down but you're not out yet. Just follow Zidane's example and you'll overturn Milan's big lead in the Champions League (we're not sure Arsenal can do it, though...)

Barcelona's defeat by AC Milan in the first leg of their Champions League knockout tie was the shock of the last 16 so far. 
Goals from two former Portsmouth players - Kevin-Prince Boateng and Sulley Muntari - have left the Catalan giants with a mountain to climb in three weeks' time.
But all might not be lost. There are a few examples from history that give the 2009 and 2011 winners hope, most notably from the 1996 UEFA Cup when a Zinedine Zidane-inspired Bordeaux dumped Milan out with a 3-0 win in France two weeks after a 2-0 reverse in Italy.

Dry your eyes mate: Lionel Messi is consoled by Milan defender Philippe Mexes at the San Siro on Wednesday

The Portsmouth connection: Milan goalscorers Kevin-Prince Boateng (left) and Sulley Muntari celebrate

Didier Tholot, plus two second-half goals from Christophe Dugarry, cancelled out first-leg strikes from Stefano Eranio and Roberto Baggio.
That was the last time an Italian side failed to press home the advantage of a 2-0 lead in Europe.

However, more recently Carlo Ancelotti's Milan conspired to throw away a 4-1 home lead when they played Deportivo La Coruna in the quarter-finals of the 2004 Champions League.

And in Barcelona's own history books, Messi and Co can find some comfort.

Barca's inspiration: Zinedine Zidane (centre) works his magic for Bordeaux against Milan in 1996

Crumb of comfort

Barcelona have only won three of their last 14 knockout games away from home in the Champions League - they even drew and lost at the Emirates in 2010 and 2011.
Still, that hasn't hurt them too much, has it?

Only on eight occasions in Champions League history have teams progressed in a knockout tie having trailed by two goals or more after the first meeting. Barcelona, though, are the only team to do it twice.

They came back from 3-1 down against Dynamo Kiev in 1993 in a first-round knockout tie to win 4-1 at the Nou Camp.

Current Swansea manager Michael Laudrup opened the scoring before a goal from Ronald Koeman and two from Jose Mari Bakero ensured future Tottenham striker Sergey Rebrov’s equaliser didn’t see Dynamo through.

Comeback kings: Rivaldo and Luis Figo led the charge as Barca beat Chelsea 5-1 at the Nou Camp in 2000

They also put an end to Chelsea’s first Champions League campaign, thrashing the English side 5-1 at home in the quarter-finals in 2000 after losing 3-1 at Stamford Bridge.

A trademark Gianfranco Zola free-kick and two goals from Tore Andre Flo looked to have secured Chelsea's shock progress, but a Barca team including Luis Figo and Rivaldo, who both scored at the Nou Camp, proved too tough for the Blues.
Only two English sides have won a Champions League tie after being two or more goals down after the first leg.

And the rest is history... John Terry and Frank Lampard celebrate Chelsea's stunning victory over Napoli

Head boy: Didier Drogba scores and celebrates at Stamford Bridge during the incredible 4-1 victory last season

Pain in Spain

Barca are in serious danger of elimination and big rivals Real Madrid are also sweating over their progress after a 1-1 first-leg draw against Manchester United.
The last time both Real Madrid and Barcelona failed to make it into the last eight was in 2007, when Milan lifted the trophy by beating Liverpool in the final.

Leeds United triumphed 4-1 over Stuttgart in 1992 after losing the first leg 3-0, and Chelsea won 4-1 at home against Napoli after collapsing 3-1 away last season before going on to win the tournament.
Arsenal, also have to turn around a 3-1 defeat following Tuesday's clash with Bayern Munich.
The Gunners have the added disadvantage of being away from home for the second meeting, and never in the Champions League have a club produced the goods that way around.

But there is hope for Celtic. As well as Milan's capitulation against Depor, Leeds' triumph over Stuttgart in 1992 is a precedent.

Good luck: Arsenal and Celtic face mammoth tasks in overturning big deficits against Bayern and Juve