Leicester City chiefs were in Portugal on Sunday for transfer talks.
Maisfutebol says among the Foxes delegation was president Vichai Sridaddhanaprabha, who was in Alvalade for talks with Sporting CP.
Leicester hope to sign both Sporting midfielder Adrien Silva and striker Islam Slimani.
The meeting broke up without an agreement, but negotiations are continuing.
Sporting president Bruno de Carvalho is willing to sell Slimani - but for nothing less than €30 million.