▶️ REACTION: Jose Mourinho

Romelu Lukaku made his debut as Manchester United cruised to a 5-2 friendly win over LA Galaxy on Sunday (AEST).

Lukaku, who joined United for a reported £75 million ($125.2 million)  from Everton earlier this month, played the second half at StubHub Center in California.

The Belgium international missed a great chance shortly after being introduced, but had an otherwise quiet 45 minutes.

Victor Lindelof also made his debut, but it was already 3-0 when the duo was introduced, with Marcus Rashford having stolen the show in the first half.

Rashford scored a brace and should have had a third to go with Marouane Fellaini's first-half goal, while Henrikh Mkhitaryan and Anthony Martial struck after the break to go with a Giovani dos Santos brace for Galaxy.

Jose Mourinho also introduced a back three in what was the UEFA Europa League champion's first pre-season friendly.

United needed just two minutes to take a 1-0 lead.

A high press led to Jesse Lingard winning the ball on the left and his toe poke released Rashford, who had time and space to place a finish into the bottom corner.

After Juan Mata forced Jon Kempin into a scrambling save, Rashford doubled United's lead.

United dispossessed Galaxy in midfield and Mata slid in the England international, who again made no mistake with a composed finish from inside the area.

Mourinho's men were dominant to begin the clash and they made it 3-0 in the 26th minute.

Lingard got in behind down the left and cut a pass back to the top of the area, where Fellaini swept in a finish.

Eyeing his hat-trick, Rashford fired over the bar from 20 yards in the 35th minute and was later denied in a one-on-one, while Chris Smalling had an effort rightly ruled out for offside.

Mourinho introduced a new 11 for the second half, including Lukaku, fellow signing Lindelof and Paul Pogba.

Lukaku had a great chance to open his account after receiving a pass from Pogba in the 49th minute, but Brian Rowe, who replaced Kempin, made a good save.

United was finding plenty of space and threatening constantly, with Lindelof volleying over from close range after a corner in the 66th minute.

The first goal of the second half finally arrived through Mkhitaryan, who side-footed a strike past Rowe after an Anthony Martial pass.

Martial also got on the scoresheet, while dos Santos netted twice for the hosts, the second deflecting off him after a David Romney header from a corner.