Cristiano Ronaldo showed "total genius" by winning a controversial penalty in Portugal's World Cup win over Ghana, FIFA technical study group member Sunday Oliseh said on Saturday.

The veteran striker went down after a tackle by Mohammed Salisu on Thursday before scoring the resulting spot-kick to become the first man to net at five World Cups.

Ghana coach Otto Addo described the penalty decision as a "gift" to Ronaldo and said it was a "really wrong decision".

"Maybe the strikers are getting smarter," former Nigeria international Oliseh told a press conference when asked why more penalties were being awarded at the tournament so far than in previous years.

"If you look at the penalty Ronaldo got, let's face it, people can say what they want about this man, but the genius thought to just be patient and put my foot to touch the ball first before you, continue my leg so that you make contact with my leg -- that is total genius.

"Let's give the strikers the compliment for getting smarter."

Nine penalties were awarded in the first round of group-stage matches.

"VAR is also a major reason why this (more penalties being awarded) is happening because the referees can now look at it three or four times and decide," added Oliseh.

Portugal take on Uruguay in their second match on Monday before finishing their Group H campaign against South Korea four days later.