Juan Mata has said that Manchester United are going through their best period since he joined the club -- and manager Jose Mourinho has changed since their Chelsea days.

Midfielder Mata worked with Mourinho at Chelsea from summer 2013 -- before the Portuguese sold him to United for £37.1 million in January 2014. The Spaniard had failed to nail down a starting place under Mourinho at Chelsea, but he has played regularly in United's recent nine-game winning streak, scoring against West Ham United and Hull City this month.

Mata said: "In terms of results, this is the best I have known at Manchester United. In terms of the confidence and the mentality we are showing, yes, it is also the best time since I have been here."

Speaking about Mourinho, he added: "He has changed. It is a different environment, it is a different club and squad. You always play depending on the different players you have.

"With this club, it has always been known that they play one kind of football -- which is attacking football and creating chances. We are doing that. He is happy with the performances.

"Everyone can see the players are playing with more confidence. He is the same person, has the same staff almost, but what has changed is the environment."

United's nine-game winning run has included six victories in the Premier League -- meaning that they have clawed back ground on the teams above them. If they defeat second-placed Liverpool on Sunday at Old Trafford, Mourinho's men will be just two points behind the Merseyside club.

Mata said: "Now we have a massive game against Liverpool. We have won nine games in a row but football has no past, you have to live in the present, and the present is Liverpool. It is always very special because of the history of both clubs. We will try to create a special game for everyone who likes United.

Juan Mata has hailed the environment Jose Mourinho has created at Manchester United. Getty

"They are doing very well. They have a very good manager [Jurgen Klopp], they have a good squad, and are playing good football. They play offensive football and it will be difficult."

Reflecting on the club's winning streak, he added: "Nine wins in a row feels very good. We are playing better. Not so good in some games but we are winning -- and, when you don't play your best game but you are winning, it is a strong mentality and this club should have that always."

The Spaniard also supported the manager's rotation of players, describing that as "very important." And he is hoping to stay involved in a new era of success.

The 28-year-old said: "We won the FA Cup and Community Shield but, when you are in a club like this, you expect to fight for everything. When I came, it was after Sir Alex Ferguson who was the most successful part of this club's history so it was not easy.

"But we feel we are getting there. The last two or three years have not been the best in the history of the club but hopefully the next ones will be very good and hopefully I can be here to live it and to celebrate very important things with this club. I can imagine it will be amazing.

"The manager said we needed to find this routine of always winning and we have done that in the last two months and we have to keep that going.

"It is not good to celebrate things too early. We are very happy with what we are doing but there are still months to go and hopefully we can celebrate at the end."