Thierry Henry has warned Mikel Arteta that Arsenal cannot produce a repeat of their showing against Sporting CP if they are to claim a positive result at Manchester City on Sunday. The Gunners booked their place in the Champions League semi-final on Wednesday following a goalless draw with Sporting at the Emirates Stadium . However, it was far from a commanding performance by Arteta's men, who were protecting a 1-0 advantage from the first leg in Lisbon last week, as they managed just ONE