Former Black Stars striker Yaw Preko says Coach Akwesi Appiah must be cautious when making substitutions during the FIFA World Cup in Brazil.

Coach Akwesi Appiah made six substitutions in Ghana’s last friendly introducing Albert Adomah, Jordan Ayew, Mubarak Wakaso, Afriyie Acquah, Christian Atsu and Emmanuel Agyemang Badu unto the pitch during the 4-0 win against South Korea.

Yaw Preko however believes the six players introduced by the coach were ineffective on the night.

“I think we have to be careful about our substitutions because those who came on in the second half were not convincing.

“We went a bit flat when they were introduced and totally changed the game which didn’t look good.

“They should have at the back of their minds at any given time so they should raise their game”

Yaw Preko currently stands as the only Ghanaian player to have recorded two different hat tricks