Rumours have swirled ever since the Red Devils midfielder has admitted it would be a dream to play for Los Blancos one day.
But now Spanish outlet AS say if Pogba is to force a move this summer United want one of two players in return.
Zinedine Zidane is reportedly looking at his squad and could be willing to let Kroos exit the Bernabeu.
And Bale is another name who has constantly been linked with United for years.
It was just last week Pogba outlined he could one day play for Real Madrid.
“Like I’ve always said, Real Madrid is a dream for anyone. It’s one of the biggest clubs in the world,” he said.
“There is also [Zinedine] Zidane as a coach and it’s a dream for anybody who likes football.
“For now, I’m at Manchester. We don’t know what the future holds. I’m at Manchester and I’m happy.”
Zidane added more fuel to the transfer gossip this weekend as he spoke about the World Cup winner.
He said: “I really like Pogba and you know that. I know him very well.
“He’s a different kind of player and he can provide many things because of his skills. He knows how to attack and defend.
“However, he’s not my player. He plays for United and we have to respect that. He’s always said that he likes Madrid.”
Pogba has impressed for Manchester United since the departure of Jose Mourinho.
The 26-year-old has netted 14 times and provided 11 assists in all competitions.
Pogba will want to perform well again on Tuesday when United take on Wolves at Molineux in the Premier League (7.45pm).