Nicolas Jackson fired Chelsea to a 3-0 win against West Ham as the Senegal striker repaid his manager’s faith with a decisive double at the London Stadium on Saturday.Jackson struck twice in the first half before Cole Palmer wrapped up Chelsea’s third win in five Premier League games under new boss Enzo Maresca.It was a well-timed brace from Jackson, who was Chelsea’s first choice striker by Maresca on Friday, despite Christopher Nkunku’s match-winning impact against Bournemouth last weekend.Although Jackson signed a contract extension earlier in September that will keep the Senegal star at Stamford Bridge until 2033, there were calls for Nkunku to start after the French forward came off the bench to net in the 1-0 win at Bournemouth.Jackson scored 17 goals in an inconsistent debut season with the Blues and was guilty of missing a number of big chances.But the 23-year-old has been in fine form at the start of this season and already has four goals in six games in all competitions.Chelsea have won all three away league games this season, losing only once, against champions Manchester City, in their five top-flight matches.Despite a reported power struggle between Chelsea co-owners Todd Boehly and Behdad Eghbali behind the scenes, former Leicester boss Maresca, who replaced Mauricio Pochettino in the close-season, has made a strong first impression.After disappointing sixth and 12th place finishes in the last two seasons, there are encouraging signs that the Italian could be the manager to turn Chelsea’s expensively assembled squad of underachievers into top four contenders.The Hammers’ dismal start to the season has already put new boss Julen Lopetegui under pressure, with the former Spain and Real Madrid boss jeered by