Belgium manager Roberto Martinez has insisted that Manchester United striker Romelu Lukaku will be given the time to prove his fitness before he selects his final squad for this summer's World Cup.

Lukaku was left out of United's starting lineup in the FA Cup final having struggled with injury towards the closing stages of the campaign, although he was named on the bench at Wembley and is expected to be fully fit by the time Belgium travel out to Russia.

Barcelona's Thomas Vermaelen was also carrying an injury at the end of the domestic campaign, but Martinez will give all of his players until the squad deadline on June 4 to prove their fitness ahead of naming his final 23-man group.

"We have to use the rules to our advantage. We are going to be preparing for Portugal, the European champions, and then on June 4 we will announce the final list of 23 players," the former Everton boss told reporters.

"This week we will work with every player individually to give them the best possible chance to be involved in the 23-man squad. Then as a group we will start the preparation we need to do with the group going to Russia.

"The idea was always to try to reduce the group to 23 from day one, but now that has changed because of the needs of certain players to give them an extra period of time to prove their fitness.

"At the moment we are open-minded with the 28 players, we will work in the same manner with everyone and then make the decision just after the Portugal game. I think that is the best way to do it from out point of view in the circumstances we have."

Belgium begin their World Cup campaign against Panama on June 18 before taking on Tunisia and England in their next two games.