But the 19-year-old did not reappear for the second half after a mixed performance in the opening 45 minutes.
However, Martindale is confident that Chukwuemeka will soon adapt to the Scottish game once he settles.
Martindale, whose team will face Hearts in the last 16, said: "Let's call it an eye-opener. He has to be more aggressive in possession.
"The boy has talent, there is no doubt about that, I've seen it in training. I can coach him into how I want him to play.
"He needs to work on the intensity and the fitness because you could see maybe in the transition the application wasn't quite there.
"That's up to me as a coach to work on that.
"I think he'll be a very good player for us but as with most foreign players and also English players coming up, I think they get a massive shock,” explained Martindale.
"You've seen it with some top players over the years and it doesn't quite work out for them."
The Lions progressed courtesy of an Ayo Obileye penalty after 16 minutes following a clumsy challenge by County defender Declan Drysdale on Bruce Anderson.
County piled on the pressure after the break but failed to take their chances, with Alex Samuel and Dominic Samuel both heading wide from good openings.