Youngsters Theo Walcott [ Images ] and Bojan Krkic [ Images ] could take centre stage when Arsenal [ Images ] visit Barcelona [ Images ] in their Champions League [ Images ] quarter-final second leg at the Nou Camp on Tuesday.

Injuries and suspensions have forced Arsene Wenger [ Images ] and Pep Guardiola into changes and their ability to adapt will be tested to the full, with the European champions holding the edge having drawn 2-2 in last Wednesday's first leg.

Arsenal are without captain Cesc Fabregas [ Images ], who cracked a bone in his leg last week, while Barca have lost Swedish striker Zlatan Ibrahimovic [ Images ], scorer of both their goals in London [ Images ], to a calf injury.

Guardiola turned to perennial substitute Bojan at home to Athletic Bilbao in La Liga [ Images ] on Saturday, when Ibrahimovic pulled out just before kickoff, 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 [ Images ] 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 [ Images ] and Gerard Pique [ Images ], who are both suspended. In their absence, Gabriel Milito [ Images ] and midfielder Yaya Toure [ Images ] could be drafted in at the back.

Eric Abidal [ Images ] 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 [ Images ] 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 [ Images ]," he added.

UNLEASH WALCOTT

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.

The Frenchman's attacking options are restricted with Andrei Arshavin [ Images ] and Fabregas both missing and Robin van Persie [ Images ] 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, who described Barcelona's first 30 minutes at the Emirates as "like a storm" 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 (on Tuesday) 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."

Arsenal suffered no fresh injuries against in the last-gasp 1-0 victory over Wolverhampton Wanderers on Saturday which kept alive their Premier League title hopes.

Probable teams:

Barcelona: 1-Victor Valdes; 2-Daniel Alves, 18-Gabriel Milito, 24-Yaya Toure, 22-Eric Abidal; 6-Xavi, 15-Seydou Keita, 16-Sergio Busquets; 10-Lionel Messi, 11-Bojan Krkic, 17-Pedro

Arsenal: 1-Manuel Almunia [ Images ]; 3-Bacary Sagna, 5-Thomas Vermaelen, 31-Sol Campbell, 22-Gael Clichy; 7-Tomas Rosicky, 17-Alex Song, 2-Abou Diaby, 8-Samir Nasri; 14-Theo Walcott; 52-Nicklas Bendtner.