Manchester City are facing Arsenal in the Premier League this weekend, and Paul Merson believes two Gunners stars need to be wary of one man. Pep Guardiola‘s side have their hardest game of the season on Sunday. Arsenal have run Manchester City close in the Premier League in each of the last two seasons, and many have tipped them to actually get the job done this time around. But Mikel Arteta’s side have already dropped points in the league and are two points behind their rivals at the moment. Key to Arsenal getting anything from the game will be how well the two centre-halves play. And Paul M…