Marcus Rashford scored twice as Manchester United began their Premier League campaign with an emphatic win over Chelsea at Old Trafford.England forward Rashford opened the scoring from the penalty spot after being fouled by Kurt Zouma.New £80m signing Harry Maguire won the ball which started the sweeping move for Anthony Martial to double the lead.Rashford made it 3-0 before new signing Daniel James scored on a bad day for new Chelsea boss Frank Lampard.Chelsea had their moments before United scored three second-half goals.The Blues hit the woodwork twice - Tammy Abraham striking the post when the game was goalless before Emerson Palmieri rattled the bar after Rashford's penalty.But United took control after half-time as they clocked up their biggest home win over Chelsea since 1965.