Chelsea have had no problems spending big on teenagers under owners Todd Boehly and Behdad Eghbali.
Chelsea could end up paying just over £50m in total for Estevao Willian after agreeing a deal with Palmeiras to sign the winger.
According to CaughtOffside, Chelsea and Premier League rivals Manchester United are both eager to sign the 17-year-old.
However, Rigg will not come cheap. The same outlet claims that Sunderland could demand up to £30m for their gem.
Rigg has made 12 appearances in the Championship for the Black Cats this season, scoring three goals. Last month, it was claimed that Chelsea had been scouting Rigg.
