ST PETERSBURG, June 30 (Reuters) - The World Cup lost its headline acts on Saturday as the game's two biggest stars, Lionel Messi and Cristiano Ronaldo, readied to leave Russia after their teams were eliminated in the round of 16.

Messi's Argentina lost 4-3 to France and hours later Ronaldo's Portugal went down 2-1 to Uruguay, leaving the tournament without its two best known and most loved players.

Given their ages - Messi is 31 and Ronaldo 33 - this could be the last the world sees of the pair, who have monopolised the world player of the year award for the last 10 years, on the biggest stage of all.

If Barcelona forward Messi, who previously quit the Argentina team in 2016 before changing his mind, does not continue until the 2022 World Cup in Qatar, he will end his career without a major trophy for his country.

After winning a gold medal with Argentina in the 2008 Beijing Olympics, many expected the little forward to take his country to glory in a World Cup or at least the Copa America.

Yet despite his brilliance - and some talented team mates -- Argentina have remained without such a trophy -- losing to Germany in the 2010 World Cup quarter-finals and suffering the same fate in the 2014 final in Rio.

While Real Madrid's Ronaldo will also be bitterly disappointed to be heading home earlier than planned from Russia, he at least has the consolation of having won his country's first ever European Championship, two years ago in France.

(Reporting by Simon Evans, editing by Ed Osmond)