Walcott has only just returned from a side strain and Fabio Capello, despite the 20 year-old scoring against Blackburn on Sunday, opted not to recall him for the senior team's weekend World Cup qualifier in Ukraine.
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Arsenal manager Arsene Wenger was upset over Walcott playing for the Under-21s in the European Championships in the summer but was happy for his player to go on international duty this week and spoke to Pearce about a call-up for the qualifier against Macedonia on Friday.
"This is the perfect opportunity for the Under-21s to support the senior team," Pearce said. "I spoke with Arsene Wenger yesterday and we both agreed it would be right for Theo to come and join the squad."
Walcott replaces Sunderland's Lee Cattermole, who has a heel problem ruling him out of the Ricoh Arena clash. Chelsea defender Sam Hutchinson was injured in Chelsea's reserve defeat to Arsenal on Monday night and will not join up with the squad.
Pearce will report back on Walcott's progress to Capello, who has picked the right-winger whenever fully fit since the former Southampton player scored a hat-trick against Croatia in Zagreb.
England Under-21 squad v Macedonia, Ricoh Arena, Coventry, Friday
Frank Fielding (Leeds United, loan), Scott Loach (Watford), Alex McCarthy (Yeovil Town, loan); Ryan Bertrand (Reading, loan), Kieran Gibbs (Arsenal), Michael Mancienne (Wolves, loan), Kyle Naughton (Tottenham Hotspur), Micah Richards (Manchester City), James Tomkins (West Ham United), Chris Smalling (Fulham); Tom Cleverley (Watford, loan), Jack Cork (Coventry City, loan), Fabien Delph (Aston Villa), Fabrice Muamba (Bolton Wanderers), Jack Rodwell (Everton), Danny Rose (Peterborough, loan), Junior Stanislas (West Ham), Jack Wilshere (Arsenal); Andy Carroll (Newcastle United), Zavon Hines (West Ham United), Daniel Sturridge (Chelsea), Danny Welbeck (Manchester United), Theo Walcott (Arsenal)