Leicester City face having to up their bid for Shoya Nakajima.
A Bola says Leicester will have to pay £36m to land Nakajima in January.
The winger was linked with a move to City in October with Wolves also said to be keen earlier in December at a time when the price was said to be around £17m.
Now Portimonense will only sell if his €40m release clause is activated.
Nakajima has scored five goals in 12 appearances for the Portuguese top flight club this season with Porto, Benfica and Sevilla also said to be keen.