The midfielder quit international football after being left out by coach Roberto Martinez for the tournament in Russia and believes that he "could have made a difference" for his country – who finished third after losing in the semi-finals to France.

Nainggolan told FourFourTwo magazine: "I deserved to be there, as I'd just had one of my best seasons ever that year with Roma. I still don't understand why I wasn't in the squad for the World Cup, which we could have won. We ended up finishing third and I believe I could have made a difference."

The former Roma star was perplexed that Martinez never explained his reasoning for omitting him from the squad.

He said: "I don't know if Martinez detested me, if he didn't like my way of playing. But he never told me why he didn't call me up for the World Cup. In a 23-man squad, how can you not find a place for a player who scored two goals in the Champions League semi-finals that year?"

Nainggolan – who now plays for Patro Eisden in his homeland – thinks that the fact that he smoked cigarettes and drank alcohol counted against him.

Asked how he felt to be watching the World Cup at home, he said: "Oh, I was terribly p***** off. I didn't pretend not to be. I knew I deserved to be a part of the group and that I could have contributed.

"Martinez probably didn't like that I was out clubbing, that I was drinking or that I was smoking. But I've always proved my level and commitment on the pitch. My private life has nothing to do with it."

Nainggolan added: "I watched it with anger and passion, and imagined what I could have given the team, especially in the semi-final loss to France, or the Japan game when we scored at the death. I'll be obsessed with it all my life."