A penalty from Cristiano Ronaldo and a stoppage time winner from substitute Goncalo Ramos saw Portugal come from behind to get the win.
"The first half was very good, technically and tactically," said Martinez when describing the match. "We controlled the match. We just missed a goal. We cancelled what Croatia did very well, which is keep the ball."
"This was the first match so intense on our part. The second half was completely different. The match was more offensive, they had the ball a little bit more than us. There was that side kick and when we concede a goal it is very easy to let Croatia dominate. After a first half like this, the dynamics are completely against it."
Martinez also hailed his substitutes, having made four of them at once shortly after the hour mark.
"In the second half we had two different matches after they scored. We used the players we have, Gonzalo Ramos, and Reuben Mendes, when he came into the pitch. We’ve seen reserve players adding a lot to the matches. We have to start well and end even better. We need to have one middle player additionally. It was why we used Reuben."
When asked whether Portugal were favourites, the Spaniard quickly refuted the claim, saying "when you look at all the round of 32, France was superior. But the other matches, what has been decisive were the details. The match against Spain will be like that."
In what was an electric crowd at Toronto Stadium, the fans were constantly bouncing and created an incredibly loud atmosphere.
Describing the stadium and facility, Martinez was quite impressed with what the stadium had to offer.
"Beautiful facilities, it reminds me of the old fashioned Premier League," he said. "Wonderful field. It’s a shame there aren’t more games in Toronto."
Martinez knew the next match against Spain in the round of 16 will not be easy, and has a plan prepared to face their Iberian rivals.
"As coach I have to set a roadmap, which is recovery tomorrow and getting ready for Spain. We respect them a lot. We are a team does self criticism, emotions were very well controlled in the second half and we know we are going to continue the next stage. We respect them."