Real Madrid have made a £137m bid to sign Paris St-Germain forward Kylian Mbappe.

The French World Cup winner, 22, joined PSG in 2017 in a transfer worth £165.7m and his contract expires in June 2022.

Mbappe has scored 133 goals in 174 games for PSG and won three Ligue 1 titles and three French Cups.

Real Madrid, who have debts of around £1bn, have so far only signed defender David Alaba on a free transfer from Bayern Munich this summer.

However, high earners Sergio Ramos and Raphael Varane have moved on, to PSG and Manchester United respectively, and Real evidently feel sufficiently confident about their finances to make an approach for one of the most highly-rated players in the world.

It is not known how the fee would be structured.

PSG, who have not yet responded to the bid, signed Argentina forward Lionel Messi earlier this month after he left Barcelona.

If Real are successful, it could trigger a number of deals before the transfer deadline.

It is known Cristiano Ronaldo's future at Juventus is uncertain and PSG are thought to be interested in the Portuguese, which raises the intriguing possibility of a link-up with Messi, his rival for the world's best player for well over a decade.

Manchester City are among the clubs to have been offered Ronaldo but are not thought to be interested in a deal.

Last week both Ronaldo and Juventus boss Massimiliano Allegri denied the forward wanted to leave.

'The deal is puzzling people'

(How this deal works) is puzzling people in France at the moment, both in terms of how PSG can reject such a huge bid for a player who is out of contract in less than 12 months, and how a club like Real Madrid, who are so deeply mired in debt, can afford to spend so much money.

We don't know how the deal is structured; there has been no indication, certainly from a French perspective of how Real are proposing to pay this 160m euros, whether it is 80m up front and 80m in bonuses, that is not clear.

I certainly don't think anyone is expecting them to pay 160m up front and of course pay Mbappe's wages on top of that, which are more than half a million euros a week.

To PSG, prestige is more important than money to their owners, from Qatar obviously. Mbappe is one of their most prestigious assets; he's a guy they really don't want to lose and it is a battle PSG are not used to losing. They've typically been able to buy anybody they want and, obviously, Mbappe is resisting. It is a bit of an alien situation to them in the 10 years they've been in charge.

My understanding was PSG had no interest in signing Cristiano Ronaldo.

They were intent on keeping Mbappe, although their stance on Mbappe does seem to have softened a bit in the last couple of days, at least behind the scenes if not publicly.

They are looking at other alternatives; Everton's Richarlison has been mentioned as one. It just seems impossible that they would sign Ronaldo on top of Mbappe, purely because of the wages he commands, but PSG are a club for whom it doesn't seem to matter at times.

If they received 160m for Mbappe then it might be possible for them to go and sign Ronaldo for a couple of years.