Belgium World Cup squad: Radja Nainggolan left out by boss Roberto Martinez

Eden Hazard, Romelu Lukaku and Kevin De Bruyne have all been included in Belgium's preliminary World Cup squad but there is no place for Roma's Radja Nainggolan.

Chelsea star Hazard, Manchester United forward Lukaku and De Bruyne of Manchester City were all named in the 28-man selection made public by national team coach Roberto Martinez on Monday.

Nainggolan, however, was a notable absentee. The midfielder -- who was only named on the reserve list for the 2014 World Cup but played in all five of the national team's Euro 2016 matches, scoring in the quarterfinal loss to Wales -- had declared last summer he was retiring from international football after being initially snubbed by Martinez.

"Very reluctantly my international career comes to an end," Nainggolan wrote on Instagram after the squad was announced. I've always done everything I could to represent my country. Being yourself can be bothering. From this day on I will be the first fan."

The former Swansea City and Everton boss did, however, call up the 30-year-old for November's friendlies with Mexico and Japan, only for Nainggolan to be forced to withdraw through injury.

After convincing performances for his club in both Serie A and the Champions League, Nainggolan featured for just over half an hour in March's friendly win over Saudi Arabia, winning his 30th cap.

"It's a tactical reason," Martinez said at a news conference announcing the squad. "Over the last two years, we have worked in a very attacking way, a very specific system and manner, and other players had those roles. Radja has a very important role in his club, and I don't feel we can give him that in the national team. He's not a player to be used in a small role."

Martinez said he had taken the unusual step of visiting Rome on Sunday to see Nainggolan in person before deciding to leave him out.

"I respect Radja," Martinez said. "He's not a young player. He's got great experience. I value his opinion.

"I didn't tell him he wasn't in the squad. I travelled to share some thoughts and the decision was made after the meeting. I was able to look into his eyes. It was a difficult conversation to have. I appreciate his honesty. I was glad to be able to see him before I made a decision."

Liverpool's Divock Origi, who spent last season on loan at Wolfsburg, and Everton forward Kevin Mirallas, who joined former club Olympiacos on a temporary basis in January, also missed out, but there was room for Christian Benteke.

The former Liverpool striker struggled for game time and goals at Crystal Palace last term, but with Manchester United's Romelu Lukaku and Chelsea's Michy Batshuayi both coming back from late-season injuries, Martinez said he needed a back-up option ahead of starting their Group G campaign against Panama on June 18 before also facing Tunisia and England.

"Christian is a player who can bring a different No. 9 style," Maritnez said of Benteke, who won the last of his 33 caps in September 2017. "Given the concerns we have over the other No. 9s, it was a necessity for us to have another one.

"He's had a difficult season, but I think he's used to working in that environment, and is experienced enough to perform for the national team. Look at the goals he scored in qualifying. He was in impressive form. We didn't call him up in March because I didn't need to see him, but it didn't affect what we thought of him."

Martinez said another of his injured players, Thomas Vermaelen, "deserves as much time as we can give him" to recover from a hamstring injury that ruled him out of Barcelona's last league game of the season.

Another defender, Lazio's Jordan Lukaku, will also be assessed at the Red Devils' training camp, which starts on Tuesday ahead of their June 4 warm-up game against Portugal.

Liverpool goalkeeper Simon Mignolet was also named to the preliminary squad despite losing his place as the No. 1 to Loris Karius in January. Mignolet, who started the friendly against Saudi Arabia, has not featured for Liverpool since January.

Martinez also had no problem including two Chinese Super League midfielders -- Yannick Carrasco and Axel Witzel -- as well as defender Laurent Ciman, who is with MLS side LAFC.

Defender Vincent Kompany, who will make his second World Cup appearance, told ESPN FC that he appreciates the way Martinez approaches his position.

"I think Roberto thinks a lot about the game," Kompany said. "He has the knowledge about the game that you can expect from a top, top manager and he gives a lot of responsibility to his players so you don't get treated like schoolchildren. You have a role to play, and with an experienced team like ours now, I think it's a good combination."

Belgium's 28-player squad

Goalkeepers: Thibaut Courtois (Chelsea), Simon Mignolet (Liverpool), Koen Casteels (Wolfsburg), Matz Sels (Newcastle United)

Defenders: Toby Alderweireld (Tottenham Hotspur), Dedryck Boyata (Celtic), Laurent Ciman (LAFC), Leander Dendoncker (Anderlecht), Christian Kabasele (Watford), Vincent Kompany (Manchester City), Jordan Lukaku (Lazio), Thomas Meunier (Paris Saint-Germain), Thomas Vermaelen (Barcelona), Jan Vertonghen (Tottenham Hotspur)

Midfielders: Yannick Carrasco (Dalian Yifang), Nacer Chadli (West Bromwich Albion), Kevin De Bruyne (Manchester City), Mousa Dembele (Tottenham Hotspur), Marouane Fellaini (Manchester United), Adnan Januzaj (Real Sociedad), Youri Tielemans (Monaco), Axel Witsel (Tianjin Quanjian)

Forwards: Michy Batshuayi (Chelsea), Christian Benteke (Crystal Palace), Eden Hazard (Chelsea), Thorgan Hazard (Borussia Monchengladbach), Romelu Lukaku (Manchester United), Dries Mertens (Napoli)