MOSCOW, June 12 (Xinhua) -- Just as each World Cup sees new heroes emerge, it also sees some players make their final bow on the world stage.

Spain defender Gerard Pique commented several months ago that he would retire from international football after this World Cup to spend the rest of his career focused on giving his best for FC Barcelona.

Andres Iniesta meanwhile recently announced he was leaving Barcelona to play in Japan, explaining he could no longer give his best every week in La Liga. The scorer of the winning goal in the 2010 final will end his career in Japan and presumably draw the curtain on his international career in Russia.

"Naturally this could possibly be my last appearance," the 34-year-old said. The World Cup contains plenty of veterans who will also make their last international appearances, with Mexico's 39-year-old defender, Rafael Marquez ending his long career, along with 34-year-old striker Oscar Peralta. Logic dictates that Egypt's 45-year-old goalkeeper Essam El Hadary will also make his last appearance for his country, bowing out as the oldest player to ever appear in the World Cup finals.

Several members of the Portugal squad could end their international careers in Russia with 36-year-old Bruno Alves, 34-year-old Jose Fonte and 35-year-old Pepe all probably playing their final minutes for their country and certainly their last at the World Cup.

Argentina's Javier Mascherano ends an international career which has taken him to four separate World Cups.

Other examples of players ending their association with the international scene are Denmark's 35-year-old Michael Krohn Dehli, Australia's 38-year-old Tim Cahill and Russia's 38-year-old defender Sergei Ignashevich. Veteran strikers Luis Tejada and Blas Perez's last World Cup appearance will also be their first as Panama debuts at the tournament.

There will no doubt be others ending their World Cup or international careers in Russia, but there are also big question marks around two of the greatest players of all time. 33-year-old Cristiano Ronaldo leads Portugal amid doubts over his future at Real Madrid after a season where he was only at his best for half of the campaign. There is a chance that the 37-year-old Ronaldo could still be around in Qatar in 2022, but for the moment it is still very much a question of wait and see.

Ronaldo's main rival Lionel Messi will lead Argentina, once again seeking that elusive major international tournament that would crown his incredible career.

The 30-year-old briefly retired from the international scene in 2016 after the centenary edition of the Copa America and is another player who could theoretically still play in 2022. But after being the focus of praise when things go well and also the target when they go badly, the question must be asked: could Messi be tempted to make this World Cup his swansong, especially if he can lead his country to glory?