Nainggolan, 30, has enjoyed a brilliant season for Roma as the club reached the Champions League semi-final and finished the Serie A season third in the table, with the midfield maestro playing a key role in that success.
However, his exploits for the Italian outfit were not enough to persuade Martinez of a call-up for the national side, with the Spaniard citing “tactical” reasons behind the exclusion.
Despite his talents, Nainggolan has only made 29 appearances for the Red Devils, while he also retired from international football last August, only to retract his decision and feature for the national side as recently as March against Saudi Arabia.
Martinez expressed his concern over the midfielder’s consistency, believing his side have been preparing for this tournament for two years, and that Nainggolan’s sporadic appearances for he national side have not been enough to justify a place in the squad.
On the decision to leave out the midfielder, Martinez told reporters: “Every player in the squad has got a different level of fatigue. That is why we will start the preparation with 28 players. The rule is that we have to give the final selection of 23 on June 4.
“We know that Nainggolan has a very important role in his club and we cannot give him that role in our squad.
“Nainggolan is a top player. The reason is tactical. In the last two years the team has worked in a specific manner. Other players had those roles.”
The Roma midfielder will miss his second World Cup in a row after failing to make the cut four years ago in Brazil.
In his place the likes of Man Utd’s Marouane Fellaini – who has five starts to his name this season – and Tianjin Quanjian’s Axel Witsel have been selected.