WATFORD, England, Dec 4 (Reuters) - Reigning champions Manchester City claimed top spot in the Premier League for the first time this season as Bernardo Silva scored twice in a 3-1 victory at Watford on Saturday. Raheem Sterling"s early header paved the way to a comfortable win for Pep Guardiola"s side who made the most of morning leaders Chelsea"s earlier 3-2 defeat at West Ham United. Silva fired in from a tight angle in the 31st minute and put City in cruise control just past the hour mark when he curled a delightful effort into the top corner. In truth City"s winning margin should have been bigger against a struggling Watford side who were given some late hope when Cucho Hernandez pulled a goal back. City"s fifth successive league win lifted them to 35 points from 15 games, one point ahead of Liverpool and two in front of Chelsea in what is shaping up to be a three-way title tussle. The sight of Guardiola"s City hitting the top in the run-up to Christmas will send shivers through their rivals. Once they climbed to the summit last season in January they marched off into the distance, although this time the form of Liverpool suggests they will not have things all their own way. "It"s still the beginning, we are not even halfway through and there is a lot of hard work to do," Silva, who is City"s surprise leading league scorer with seven goals, said. "It"s always better to be top of the league than second, third or fourth, but it"s so close -- Liverpool are just one point behind us, Chelsea are two points behind us. "But we are in good form and we want to keep it that way." LONG NIGHT It was only a fortnight ago that Claudio Ranieri"s side put Manchester United to the sword at Vicarage Road. But they barely got a kick in the first half against City. Once Sterling was given the freedom of the penalty area to head in Phil Foden"s cross after four minutes it always looked like being a long night for the hosts. Jack Grealish could have had a hat-trick before halftime as he wasted several glorious chances but Silva soon showed him how to find the back of the net. The Portuguese playmaker"s astute pass set up a chance for Ilkay Gundogan whose shot was saved by Daniel Bachmann but as the ball came out Silva was alert to drill a low shot into the net from an acute angle. His second was a thing of beauty. Taking a pass from Kyle Walker on the right, Silva cut inside Danny Rose and curled a shot into the top corner with almost nonchalant ease. City switched off slightly to allow Hernandez to score after his shot came back off the post, but it was a minor hiccup on a thoroughly satisfying day.