Jose Mourinho has accused the officials in Manchester United's International Champions Cup meeting with Liverpool of having expected a game of "baseball" instead of football.

The Red Devils succumbed to a 4-1 defeat at the hands of their Premier League rivals in Saturday's game at the Michigan Stadium in Ann Arbor.

In front of a bumper crowd of 101,254 at the venue known as the 'Big House', two penalties contributed to United's defeat, and Mourinho was irate regarding the decisions.

"The referees, they came by mistake - they were called by the baseball federation, thought it was a baseball game," the Portuguese told reporters after the game.

"They arrived here and it was soccer and they had to be in a soccer game. So, it was good fun."

The defeat to Liverpool was United's first of their pre-season campaign.