Former Arsenal star Jermaine Pennant has warned the club's latest teenage sensation, Theo Walcott, it will not be easy to make the grade at Highbury.Pennant, signed for £2million from Notts County six years ago, failed to make the breakthrough into the first team on a regular basis under manager Arsene Wenger. The skilful winger, now with struggling Birmingham, also claims that the French coach is not the best at allowing young talent to develop with a number of the club's FA Youth Cup winning side forced to leave. Arsenal could eventually pay £12million for Walcott after landing the Southampton striker for a record fee for a teenager last week. The wonderkid is cup-tied for Arsenal's Carling Cup semi-final, second leg against Wigan at Highbury tonight and Pennant warned: 'I wish him all the best - but it is not going to be easy. 'Are Arsenal the best club to develop at? Things did not work out for me so it would be hard for me to say but the club has got a lot of faith in him and they will try to nurture him as best as possible. 'When I was there, my FA Youth Cup team won the competition two years in a row and there is nobody to show for it playing now at Arsenal. 'Everyone has gone elsewhere - Steve Sidwell, David Noble, Jay Bothroyd, a lot of players, I could keep on going. Only Ashley Cole has come through from the youth ranks so I don't know if the youngsters do get a chance but we will see what happens with Walcott.' Meanwhile Wenger, who has swapped youth for experience for tonight's crucial semi-final, has backed new signing Emmanuel Adebayor over his decision to stay with Togo in the African Nations Cup. Adebayor was ready to walk out on his country after being left out of the starting line-up against the Democratic Republic of Congo in their first game. But the player relented and is now preparing for Togo's second game against Cameroon with Wenger adamant that his new addition made the right move. 'He missed their training but he has made the right decision to stay and fight for his international team in their second game and we will assess the situation after that.' Wenger will hand captain Thierry Henry his first league cup start for over six years against Wigan. Arsenal trail by a single goal against their Barclays Premiership rivals and Wenger has opted to dispense with the policy of playing young kids as he bids to try to reach the final. The competition is the only domestic trophy Wenger has failed to win during his time as Arsenal boss and he is desperate to put that right. Goalkeeper Jens Lehmann has been rested for the tie but Wenger is boosted by the return of Dutch striker Robin van Persie from a broken toe. Wenger will also keep faith with the defence which failed to prevent James Beattie hitting the matchwinner at Goodison Park in the Premiership on Saturday. 'In this competition, I have always put out a side to win the game,' declared Wenger. 'This time the adjustment needs to be strong. We lost the first game 1-0 and we want to go through to the final. Therefore you will see a few experienced players. 'Lehmann will not play, Almunia is in. But (Sol) Campbell and Henry will certainly play. (Robert) Pires is in the squad but I don't know if he will start or not. You will see the same defence as Saturday. We have not much choice, especially with the left-footed players out plus Kolo Toure and Emmanuel Eboue being out for the African Nations Cup.' Henry, rested for the opening game, has promised an attacking evening as the Gunners aim to cancel out Wigan's aggregate lead early on. 'I watched the Wigan game but we are only at half-time,' said Henry. 'Of course it would have been nice to have come back with a draw or a win, but now we have got them at home, we know exactly what we have to do. 'We will have a go at them and change the tie. It was a strange game at Wigan because I expected them to be more aggressive. It seemed that both teams were waiting for each other. I am sure they did not want to concede and so it was not like a proper cup game because there was still the return to think about.' Goalkeeper Mart Poom, signed on a permanent deal yesterday after impressing on loan from Sunderland since the start of the season, is also included in the squad.