By Chris Harris

The midfield battle will hold the key to tonight's Champions League Quarter-Final, according to Arsène Wenger.

Arsenal and Barcelona are locked at 2-2 ahead of the second leg in the Nou Camp and the European champions are firm favourites to prevail after bossing much of last week's game at Emirates Stadium.

Spanish international Xavi pulled the strings in the first leg while the unsung Sergio Busquets and Seydou Keita worked quietly but efficiently alongside him. Arsenal failed to close that triumvirate down quickly enough last week and Wenger knows that will have to change this evening.

"We know that when we don't have the ball you need everyone on board, especially against Barcelona and on a pitch like the Nou Camp," said the Frenchman.

"We have to make the pitch smaller and everybody must work hard to win the ball back. That's where we failed in the first game last week, especially in the first half and of course the heart of the battle will be won in midfield.

"That's where they have the players who can dominate the game, especially Xavi, and a big part of the game will be decided there."

Copyright 2014 The Arsenal Football Club plc. Permission to use quotations from this article is granted subject to appropriate credit being given to www.arsenal.com as the source 6 Apr 2010