Manchester United midfielder Ander Herrera has said that he respects manager Jose Mourinho's comments regarding a lack of transfers and first-team players available on their pre-season tour.

United have signed Brazilian midfielder Fred and goalkeeper Lee Grant so far this summer, but it is understood that Mourinho wants two more signings from his board before the start of the 2018-19 Premier League season.

Mourinho has also voiced his frustrations regarding the lack of key players on their pre-season tour, including the likes of Paul Pogba, Nemanja Matic and Romelu Lukaku, who are on holiday following the World Cup.

"First of all, I have to respect what my manager said, because he knows what he's talking about," Herrera told reporters ahead of their friendly against Real Madrid.

"Secondly, I am a football player. My work is on the pitch, not in the office. The other things, they are too far from my hands. So, I think we have fantastic players, but, of course, always managers want to improve their teams, but it's not my business.

"I can say that with us he is very positive, he wants us to fight for the titles, he wants us to perform to our best, he wants us to work as hard as possible. But probably he's not frustrated about the club or the market, he's probably frustrated because he's not able to work with the players that he's going to have for the season."

The Red Devils have until August 9 to sign more players, and will face Leicester City at home on August 10 in their opening league fixture.