Jose Mourinho has stars in his eyes after dazzling Paul Pogba performance

United were convincing 2-0 winners over Southampton at Old Trafford, Zlatan Ibrahimovic on target with header and a penalty to take his Premier League tally to three in two games.

But all eyes were on Pogba, the world's most expensive footballer at £89million, as he debuted for the second time with the Red Devils.

His big day began with an error, a sloppy first touch gifting Southampton possession in the opening seconds, but he shone from there on and dominated the midfield with an all-action display.

"He was fantastic," said Mourinho of the France international.

"The fact his first action was bad - he loses the ball, gives a counter to the opponent - means you could see even more the ego, the personality... he's so comfortable under that skin of a star.

"He is so confident, the way he plays. He was phenomenal."

Mourinho had not intended to use Pogba for the full 90 minutes but saw no reason to call an early end to his happy homecoming.

He began in a deep-lying midfield role but roamed wherever he saw fit, supporting the attackers, covering Luke Shaw on the left flank and working with Marouane Fellaini to shield the back four when required.

In the end, even his own manager was left at a loss to describe his role.

"I don't know which position he played," admitted Mourinho with a smile.

"He has to play free, but for a player to play with freedom we have to build organisation around him."

Speaking to BBC Sport after the game, Pogba reflected on his return with satisfaction and predicted a successful season ahead.

"It's a great feeling, I'm very happy," he said.

"I was relaxed, no nerves, I played my game. I came here to win, that is what I always wanted. It's a top club and we need to get used to winning and carry on like this. First ball, I lost it, but got used to it. After that I felt better. We dream big. United are a big club, I know we will do big things this season."

Alongside Pogba in the United engine room was the revitalised Fellaini, a character reviled by fans for much of the last three seasons.

After two impressive showings to start the season he suddenly seems a player of importance, an upturn that started with a message of support at the start of Mourinho's reign.

"The player was feeling not loved," said Mourinho.

"When the market opened everybody was saying he was leaving, everybody was writing he was not the player for me, he was on the move, maybe a simple phone call the day after my presentation changed a lot. I told him just simply 'forget everything you read, forget everything, with me you don't leave for sure'. Maybe that word of confidence was unexpected for him."