There has been speculation about Pogba's Old Trafford future after he spoke of finding "a new challenge" in June, while his agent has said the France international wants to leave.

But pre-season has been going well for the squad, said Spaniard Mata.

"He's a fantastic midfielder and he's a very good guy," the 31-year-old added.

"I think he's happy."

Earlier in July, United manager Ole Gunnar Solskjaer also said Pogba has "never been a problem" and claimed there is an "agenda" against the player.

Mata wants 26-year-old Pogba's future to include helping the club to start lifting "big trophies" under Solskjaer, after two seasons without winning anything.

"Obviously as a team-mate, and as a friend also, I would like him to stay and to be happy because he is a very good player for us," the 31-year-old Spain international, who signed a two-year contract in June.

"We know we have to do better than last season. This club has won more trophies than any other club in England."

United have not won the Premier League since 2013, the year Sir Alex Ferguson retired, and their last major trophy was the Europa League in May 2017 under Jose Mourinho - three months after winning the Carabao Cup.

Solskjaer is Mata's fifth manager at Old Trafford - an amazing statistic given the club prided itself on stability under Ferguson, who was manager for 26 and a half years.

David Moyes was in charge when the midfielder joined United from Chelsea for a then club record £37.1m in January 2014 and he has since served under Ryan Giggs, Louis van Gaal, Mourinho and Solskjaer.

"The feeling of being a Manchester United player is so unique," added Mata, who committed his future to United despite receiving lucrative offers to move elsewhere.

"I am very happy to stay here. I am dreaming about winning big trophies at this club. That is what the fans deserve.

"We want to win big trophies again. That is what the history of this club deserves."

United finished sixth in 2018-19, which means they will play in the Europa League this season.

However, Mata decided to stay and fellow Spaniard, goalkeeper David de Gea, is also on the brink of signing a long-term deal.

"David is the best or one of the best goalkeepers in the world, for sure," Mata said.

"He is one of my best friends, so I want him to stay. On a professional level, it will be great for us if he stays because he will give us many points over the next seasons."

Midfielder Ander Herrera has moved on, though, joining Paris St-Germain after his Old Trafford contract expired.

Solskjaer is keen to introduce more youngsters into the first-team squad during 2019-20.

Teenage striker Mason Greenwood has been guaranteed a future by the Norwegian and added to his growing reputation on Saturday when he scored the winner against Inter Milan in the pre-season International Champions Cup in Singapore.

"Mason has a lot of qualities and the most important one is his mentality," added Mata.

"He's hungry to improve and to give his all for the team.

"We are very happy he's finding his feet in the first team and gaining confidence. I am sure he'll score many goals for this club."