Will they rise to the occasion?

Guardiola turned to perennial substitute Bojan at home to Athletic Bilbao in La Liga on Saturday,when Ibrahimovic pulled out just before kick-off,and the 19-year-old scored twice in a 4-1 win. “He always scores when he is played in his position (striker). I feel a little indebted to him because he always rises to the occasion,” Guardiola said. “But he is young and has a lot to learn. We don’t forget this.”

With Thierry Henry still struggling to convince Guardiola of his commitment to the cause,not helped by a largely anonymous second-half appearance at the Emirates Stadium,Bojan could start up front. Barca are without central defensive pairing Carles Puyol and Gerard Pique,who are both suspended. In their absence,Gabriel Milito and midfielder Yaya Toure could be drafted in at the back. Eric Abidal played his first game in over six weeks after injury on Saturday and should return at left-back. Barca visit La Liga title rivals Real Madrid on Saturday for a top-of-the-table clash,but Guardiola was clear where his priorities lay. “Tuesday is the most important game of the year,more than the Bernabeu,” he added. Wenger will be tempted to unleash Walcott,21,from the start in the Nou Camp as the jet-heeled winger made a huge impact after coming on in the second half last week.

Restricted options

The Frenchman’s attacking options are restricted with Andrei Arshavin and Fabregas both missing and Robin van Persie not yet ready to return and but he must decide whether Walcott is best used from the start or as an impact substitute. Needing to win or achieve a high-scoring draw to go through,Arsenal will hope to capitalise on Barcelona’s defensive absentees although Barca’s firepower could signal a more cautious approach from Wenger. “You have big players on the bench,” Wenger told the club’s website. When they come on you don’t forget they have qualities to make an impact. Theo has a chance to start the game but he can as well come on again and make a difference. If it is 0-0 with 20 minutes to go,we will need players who can make a difference.”

In the night’s other match,Inter Milan travel to Moscow with a 1-0 lead and will attempt to knock out CSKA Moscow on their way to the semi-finals.