Chelsea's £26m bid for John Stones could see the Everton youngster become one of the most expensive defenders in history.
Only 13 transfers involving defenders have seen a reported fee of £20m or more change hands.
Should the Stones deal go through at £26m it would leave him as football's ninth most expensive defender.
The deal would be ahead of the one which took Mehdi Benatia from Roma to Bayern Munich last year (£24m), Lilian Thuram's 2001 move from Lazio to Juventus (£23m), Alessandro Nesta's 2002 transfer from Lazio to AC Milan (£21m) and Ricardo Carvalho's in 2004 from Porto to Chelsea (£20m).
Stones' deal would still be some way off the record though - David Luiz's £50m move Chelsea to Paris St-Germain last year.
The transfer of Thiago Silva from AC Milan to PSG (£35m) is the second largest on record, Eliaquim Mangala from Porto to Manchester City (£32m) comes third and Rio Ferdinand's move from Leeds United to Manchester United (£30m) comes fourth.
Some of these transfers were over 10 years ago though, so how does Stones' fee compare if we adjust previous deals for inflation?
David Luiz would still be top of the pile on £50m.
However, Rio Ferdinand's 2002 transfer would have cost £43.6m in today's money and as such would have made him the second most expensive defender in history as opposed to the fourth.
The 2001 transfer of Lilian Thuram to Juventus would have cost £33.97m when adjusted for inflation and therefore would be the fourth most expensive after Thiago Silva (£36.9m).
Dani Alves' 2008 transfer to Barcelona from Sevilla would have cost £33.96m today, which would make it the fifth most expensive on record.
Stones' £26m fee would leave him ahead of only Mehdi Benatia (£24m) with Ricardo Carvalho leapfrogging him as his deal would be worth £27.4m when adjusted for inflation.
The transfer fees quoted in this article are taken from media reports at the time of the transfer. Agents fees and performance related payments may not be included.