HOUSTON -- Here's what we learned in Manchester United's 2-0 International Champions Cup win against Manchester City on Thursday night.

Lukaku and Rashford, a return to twin strikers?

It has been a while since twin strikers were the fashion, with false nines and solitary front men dominating the scene in recent years, but Jose Mourinho believes Romelu Lukaku and Marcus Rashford can play together up front. The Manchester United pair backed up their manager's theory in Houston.

They both possess pace and power, with Rashford more inclined to work across the front line than his new £90 million teammate, but their first-half goals against Manchester City at the NRG Stadium also highlighted their ability to put the ball in the back of the net.

Lukaku's finish from a tight angle after goalkeeper Ederson had rushed out of his penalty area was sublime, world-class goal scoring, while Rashford was clinical two minutes later, shooting past the Brazilian keeper from 10 yards following Henrikh Mkhitaryan's pass.

Playing with two strikers went out of fashion because teams began to pack the midfield, leaving managers wary of being short in the centre of the pitch by having two players up front.

But as Andy Cole and Dwight Yorke proved by inspiring United to the Treble in 1999, when it works well, two up front can be unstoppable.

Defending an issue for both City and United

Vincent Kompany gave a defensive master class during his 45-minute outing in Houston, but the Manchester City captain is a rarity in the modern game in that he can defend and keep mistakes to a minimum.

John Stones looked shaky in the second half, while United's Chris Smalling was also unconvincing during the first half for Mourinho's team.

And Victor Lindelof, United's £30.75m summer signing from Benfica, struggled to impress, with the Sweden international careless in position and suspect positionally against Sergio Aguero.

At full-back, Kyle Walker impressed for City and looked a real upgrade on Pablo Zabaleta and Bacary Sagna, but Eliaquim Mangala was given the runaround while playing out of position at left-back after the interval.

On the red side, Daley Blind continues to fill a gap at left-back, despite looking as though he would rather be somewhere else.

Mourinho was able to marshal United into a tight defensive unit last season, but with Marcos Rojo out until the autumn, they still look vulnerable at the back.

Man United players celebrate after Marcus Rashford scored their second goal against Man City. no_source

Ederson starts like Claudio Bravo

If Ederson could have had one wish before his debut as Manchester City goalkeeper, it would have been to make a better start than Claudio Bravo.

But just as the Chilean set alarm bells ringing during his first game for City in last season's derby win against United at Old Trafford, Ederson also had one of those moments to forget which could yet come back to haunt him.

The £34.7m signing from Benfica is regarded as Brazil's goalkeeper for the next decade, but he was reckless on 37 minutes when he raced out of his area in an attempt to intercept Paul Pogba's long pass forward to Lukaku.

Ederson missed the ball completely, 30 yards from goal, and left Lukaku with an open net, albeit from a very tight angle. Lukaku buried the opportunity, though, so Ederson's mistake was a costly one.

And although Rashford beat him with power and precision when scoring United's second, two minutes later, Ederson suddenly looked like Bravo -- the keeper who hardly saved any shots last season.

Ederson clearly has great potential, but his decision-making was exposed by Lukaku's goal, and only experience and maturity can fully eradicate that flaw.