Manchester City boss Mark Hughes credits Stephen Ireland's flying form to the arrival of Robinho.
He said: "Good Premier League players look at top players coming into their club and view it as a challenge.
"Players are quickly looking to see if another player is as good as people say he is. 'Will he help us to win games?' The answer is he will do. And the players are responding. Look at how well Stephen Ireland is playing.
"He has been exceptional since I came here. He has been arguably our best performer.
"We have raised the bar and set a high standard and we will maintain it with the work ethic we have."