Manchester City struck two early goals before seeing off a heavy snow storm to open up a three-point lead at the top of the Premier League.Sergio Aguero opened the scoring from the penalty spot after Adam Johnson had been tripped by Chris Baird.Baird then doubled the lead when he turned Johnson's cross-shot beyond his own goalkeeper Mark Schwarzer.Play had to be halted twice to allow ground staff to clear snow from the lines before Edin Dzeko added a third.