Arsenal hero Martin Keown believes Arsene Wenger has found a way to mark Barcelona star Lionel Messi out of any game.
Keown saw his former club shock Barcelona 2-1 on Wednesday.
He wrote in his column for the Daily Mail: "Lionel Messi is so hard to mark because he drops so deep into the midfield and no-one can pick him up. You are taught as a defender to never run that deep with a player - it is against the rules - but you have to rip up the rule book with Messi.
"Arsenal did just that in the second half.
"Johan Djourou and the excellent Laurent Koscielny made a conscious decision to go deep with him after the break and it worked as the Argentina playmaker was no longer a threatening, unmarked spare man.
"It is a tactic Lucio employed brilliantly for Inter Milan when they beat Barcelona in the semi-final last season and something Arsenal will have to do again in the second leg on March 8."
