Money in football is forever on the rise.

Back in 2009, Cristiano Ronaldo became the most expensive player in history by joining Real Madrid from Manchester United for £80m.

Fast forward to 2017 and Neymar smashed the transfer record in a £198m move from Barcelona to Paris Saint-Germain.

It won't be long before the £200m mark is surpassed - and we're seeing the same kind of rise when it comes to players' wages.

Wayne Rooney was United's highest-paid player on £180,000-per-week in 2010; now it's Alexis Sanchez, who earns an eye-watering £500,000-per-week and £25m-per-year.

Premier League clubs are richer than ever before and able to pay their players more as a result, which has raised a big issue.

A recent report from Citizens UK, per iNews, revealed that only four out of 20 clubs in the Premier League are accredited with paying all their staff the Living Wage.

Third-party employees like cleaners, match-day workers and security staff are among the lowest paid at Premier League clubs and the most affected.

The national living wage for over 25s is £8.21 an hour, yet one anonymous cleaner at Old Trafford was quoted as saying they earn just £7.80.

Compare that to Sanchez, who earns an outrageous £2,500 an hour at United, and you can see that something is fundamentally wrong.

Liverpool, Chelsea, Everton and West Ham are the four clubs accredited by the Living Wage Foundation with formally committing to paying all staff at least £9-per-hour.

Tottenham have also committed to paying everyone the Living Wage but aren't yet accredited by the LWF.

It's time for the other 15 Premier League clubs to do what's right. Even if paying the Living Wage is voluntary, paying out an extra £2 an hour to third-party staff would be a drop in the ocean.