Chelsea are chasing French pair Raphael Varane and Eliaquim Mangala.
The London Evening Standard says the central defenders are part of the France squad for today's last-16 tie against Nigeria in Brasilia and Chelsea boss Jose Mourinho wants one of them to provide more competition to captain John Terry, Gary Cahill and Branislav Ivanovic.
Chelsea have been interested in Varane and Mangala for some time and both have indicated they would consider a move to Stamford Bridge.
Real Madrid do not want Varane to leave but he enjoyed a close relationship with Mourinho while he was in charge at the Bernabeu and is aware of Chelsea's pursuit.
Porto's £35m asking price for Mangala could be an issue but the defender has already revealed he wants a move to west London, despite rival bids from Manchester City and Manchester United.
