The newspaper claims Swansea City thought they had a deal for Nmecha, with Blackburn Rovers and West Bromwich Albion also interested in the striker.
It adds, however, that Nmecha was yesterday (Thursday) cleared for talks with Leeds, and that Guardiola's relationship with Marcelo Bielsa, his Whites counterpart, may prove decisive.
Should the 19-year-old move to Leeds, he would follow in the footsteps of Jack Harrison - the Manchester City winger who switched to Elland Road on a temporary basis last week.
It is not the first time the Sun has linked Leeds with Nmecha's services this summer.
The newspaper reported in June that the German-born England youth international was one of three players Guardiola was ready to send across the Pennines, along with Tosin Adarabioyo, the defender, and Brahim Diaz, the attacking midfielder.
Adarabioyo, however, has today signed for West Bromwich Albion on loan instead.
Would Nmecha be a good signing for Leeds?