Bayern Munich will test Everton's resolve over their best defenders.
The Sun says the German giants are planning a £10million raid for England defender Leighton Baines, 26, in next month's transfer window.
But Goodison chief David Moyes is desperate to keep his in-form left-back, who signed a five-year deal at the end of last season.
Bayern have made a dire start to the Bundesliga campaign and are 17 points off the top.
Bayern chief executive Karl-Heinz Rummenigge insists a quality left-back is his priority and his spies have been impressed with Baines, who switched to Goodison from Wigan in a £5m deal in 2007.
The German club have also confirmed their interest in Dutchman Johnny Heitinga, 27, and the centre-back has said he is interested in the move.
