Harry Kane, Christian Eriksen and Dele Alli are generally regarded as Spurs' key trio in the final third, but Son has enjoyed the best season of his career, with 18 goals being scored in 44 appearances in all competitions.
Son has recently held down a first-team place at the North London outfit, and South Korea teammate Ki - who plays for Swansea City - has described the attacker's recent performances as "amazing".
The 29-year-old told reporters: "In my opinion he of course has to get more credit. I don't say that Harry Kane and Dele Alli are worse than Son. They are all top players but I think Son has to get more credit in my opinion.
"His performance this season has been amazing. Everyone knows he plays one of the best games and is very consistent in every game and he scores many goals for Spurs which is not easy."
Both Ki and Son are expected to feature when South Korea face Northern Ireland on Saturday afternoon.