Arsene Wenger has backed forward Theo Walcott to become a "great football player" for Arsenal - and England.Walcott has been hampered by injuries and a dip in form, and after the match against Egypt said he may struggle to make England's World Cup squad. [LNB]However, the Gunners boss is convinced Walcott, 20, will progress: "I believe Theo will be a great player, he is young, he will have a great future. [LNB]"For a while people expected too much and now they are too hard with him." [LNB]Wenger reiterated his belief in his young attacker after former England winger Chris Waddle questioned Walcott's England credentials, claiming the Arsenal man "doesn't understand the game". [LNB]"Don't worry for him," added Wenger of the player who cost the Gunners £5m when they signed him from Southampton in 2006.[LNB] "I believe for a while maybe people expected too much of Theo and now they are too hard with him," Arsene Wenger "I believe Theo has not only a football brain, but he has a brain - that means he will continue to develop at a very quick pace. [LNB]"I believe in him because he has a fantastic attitude, he's an intelligent boy and highly motivated." [LNB]The winger's season has been hampered by injuries to his back, knee, hamstring and ribs, but Wenger has previously stated his belief that England boss Fabio Capello will include him in his squad for the World Cup in South Africa this summer. [LNB]After returning to fitness with Arsenal, Walcott started for England in Wednesday's friendly against Egypt at Wembley before being replaced by Shaun Wright-Phillips after 57 minutes. [LNB]Capello must pick an initial 35-man World Cup squad by 12 May, with a 1 June cut-off date set by Fifa for teams to name their final 23-man squads.