Radja Nainggolan believes Roberto Martinez's decision to not select him in the latest Belgium squad was "strange."
Martinez announced his squad for the upcoming games against Netherlands and Estonia on Friday, with Nainggolan, 28, missing from the selection.
The Spaniard said he chose to omit Nainggolan due to fitness issues, but the Roma midfielder feels he was in the right shape to be selected.
"I had a pretty good European Championship, I scored two important goals," Nainggolan told Het Nieuwsblad.
"Against Bosnia [and Herzegovina] and Gibraltar in October I was not fit, now I am. However, the coach called me stating I was not fit enough. I thought that was strange and I told him that. I have played the last four games for Roma and scored another goal on Thursday.
"This is a disappointment. I like to play for the national team and fit in the group well. With [Steven] Defour and [Mousa] Dembele injured or just back from injury, I had hoped to play against Netherlands."