Raheem Sterling made his Arsenal debut as he came on as a second-half substitute in the 1-0 win against Tottenham Hotspur. Gabriel Magalhaes’ close-range header was the solitary goal of the game in the North London derby as Mikel Arteta’s side made it three wins and a draw to keep pace with Manchester City at the summit. Sterling was introduced with ten minutes left on the clock for Gabriel Martinelli as he attempted to get on the ball and run at tired legs. While he didn’t have too much to do in the short time he spent on the pitch, Martin Keown believes the England international is not up to…