The young Blues defender turned in a composed performance to help nullify the threat of the likes of Carlos Tevez and Fernando Llorente - before emerging as a penalty shootout hero.
Martinez told evertontv: "I knew he was going to do it because the last three he has taken in training he has done that. The question was could he do it after Andrea Pirlo and at his age.
"It was incredible and I thought it was an example of his performance. He was composed throughout and it was a very useful game for himself and (he could be) a very important 'new' player for us going forward."