Neymar, serene amid a frenzy of transfer speculation, scored the first-half goal that gave Barcelona a 1-0 victory over Manchester United on Wednesday in an International Champions Cup friendly.

The Brazilian striker, reportedly pondering a 222-million euro ($256.8 million) move to Paris Saint-Germain, showed why the French club would be willing to pay a world-record price to get him.

He delivered his third goal in two matches in the exhibition tournament as Barcelona handed the English Premiership club their first defeat of the pre-season.

After a bright start Manchester United struggled to contain Barcelona's star duo of Neymar and Lionel Messi.

Neymar broke through in the 31st, stripping the ball from Antonio Valencia in the penalty area, turning and finding the net.

The goal proved enough to give a second straight victory to new Barcelona coach Ernesto Valverde.

Valverde made sweeping changes to the team that beat Juventus 2-1. Luis Suarez, Jordi Alba, Samuel Umtiti, Nelson Semedo, Sergio Busquets and 19-year-old midfielder Carles Arena were included in the lineup headed by Messi and Neymar.

There were eight changes to the Manchester United team that defeated Real Madrid on penalties on Sunday, with captain Michael Carrick, Marcus Rashford and Jesse Lingard the only players to retain their starting spots.

It was Manchester United who threatened first, when Rashford's cross found Romelu Lukaku in the area, but the Belgian couldn't find the net.

Barcelona inexorably took control, and United goalkeeper David de Gea was given plenty of work by Neymar, Messi and Suarez.

Messi came close in the 12th minute, his low effort sliding wide.

A long-range effort from Lukaku, a fierce blast from Paul Pogba and a curling effort from Rashford all tested Barcelona keeper Jasper Cillessen in the space of minutes.

But from there Barcelona dominated. De Gea denied Neymar from close range in the 28th, but had no answer for the Brazilian three minutes later.

Valencia had got control of a pass from Messi, but Neymar was there to regain the ball, turning in close quarters and firing past de Gea to the delight of the Barcelona fans among the 82,000-strong crowd at FedExField -- home of the NFL's Washington Redskins.

Three minutes before the break de Gea parried Suarez's scissor-kick to keep it 1-0 to Barcelona at halftime.

Both coaches rang the changes at halftime, with Valverde replacing 10 players -- only leaving Cillessen in goal.

Jose Mourinho made five changes in his Manchester United side, and the second half moved at a slower, less fluent pace.

Anthony Martial, Andreas Pereira and Pogba all threatened, but Manchester United were unable to find an equalizer.

Pre-season Clasico

The match was the last of Manchester United's US tour -- which included wins over Real Madrid, Manchester City and Major League Soccer's Real Salt Lake and Los Angeles Galaxy.

They are due to take on Valerenga in Oslo on Sunday and then Sampdoria in Ireland before facing Real Madrid in the UEFA Super Cup on August 8.

Barcelona, meanwhile will take on Spanish rivals Real Madrid in a pre-season "Clasico" in Miami on Saturday -- apparently still uncertain just how long they will have Neymar to rely on.

Man United’s first preseason defeat

United's defeat at the FedexField was their first in their pre-season campaign.

"It's very important to lose a match in pre-season," Mourinho told reporters after the match.

"I think it would be very bad for us to leave the U.S. without a defeat, playing against teams like Real Madrid, Barcelona, Manchester City, it would be very bad to go home with just victories.

"I think in the game we did some very good things and we did bad things. The very good things are to keep and the bad things are to improve."

Mourinho was particularly impressed with another solid display from midfielder Paul Pogba, who the Portuguese manager believes is among the best players in the world.

"(Lionel) Messi and Neymar, there is only one; there is not two. (Luis) Suarez, (Andres) Iniesta, (Gerard) Pique, (Cristiano) Ronaldo, (Gareth) Bale, (Luka) Modric, Toni Kroos; there is only one so they can only play for one club, not for two clubs," said Mourinho.

"We can't have them, they belong to the clubs. But I have to say that Paul Pogba showed the level... he showed he belongs to that level."

The United manager also confirmed midfielders Juan Mata and Ander Herrera will resume training when they return to Manchester on Saturday.

Mourinho's side will next visit Norwegian side Valerenga on Sunday before facing Italian Serie A team Sampdoria in their final pre-season match in Dublin on Wednesday.

They kick off their competitive campaign with a UEFA Super Cup meeting with Real Madrid on Aug. 8 in Skopje.