Big money summer signing Romelu Lukaku announced his arrival at Old Trafford by scoring twice on his Premier League debut for Manchester United as they embarrassed West Ham.
On a day of high expectations on both sides, Jose Mourinho's team were a constant threat against a poor Hammers side, offering excitement and encouragement to their supporters on the opening weekend of the new Premier League season.
Lukaku, a £75m summer signing from Everton, put the Red Devils ahead with a rising drive off the post after racing onto Marcus Rashford's pass before half time.
The Belgium international doubled the lead after half-time, glancing in a header from Henrikh Mkhitaryan's inswinging free-kick.
United teenager Rashford hits the post before substitute Anthony Martial ended the match as a contest with a lovely finish.
There was still time for a fourth, however, as Paul Pogba stood up to provide it with a curled in from distance.
The Hammers offered little going forward in a passive performance, although new signing Marko Arnautovic did flick a header onto the top of the home crossbar at 2-0.
The Red Devils have now lost only one of their 14 opening-day Premier League fixtures at Old Trafford, while West Ham's season began with a record 11th defeat.