"Messi is one game-changing performance away from reminding the world why he is still one of the most sought-after brand ambassadors on the planet," said Andy Sutherden, global head of sports and partnership marketing at Hill and Knowlton Strategies in London. The World Cup was just "a short-term blip," he said.
While Ronaldo, who has built up an image of arrogant power with Real Madrid, has carried the Portuguese national team to the verge of the second round by scoring all four of their goals, Messi, the modest, dribbling genius of Barcelona, has been conspicuous by his inability to contribute for Argentina.
On Football Index, a trading game website where participants can buy and sell players, Messi's price has fallen 4 percent since before the tournament while Ronaldo is up 6 percent.
But in the real world, both the value of the player to club employers and to marketing sponsors is less volatile.
"The financial value for the most established players is more of a structural nature. There is not a big change if he scores a goal," said Raffaele Poli, head of the CIES Football Observatory in Switzerland, who has analysed transfer markets.
He values Messi at 184 million euros ($214 million), almost double Ronaldo, who is three years older. Those values do not change quickly, he said: "Next week, Messi scores a hat-trick and Ronaldo misses a penalty. The market is completely logical."
Ronaldo's off-field earnings, notably around the CR7 logo combining his initials and his shirt number, saw little clear drop after a poor showing for Portugal at the 2014 World Cup.
A Forbes magazine ranking of athletes estimates Ronaldo earns $47 million a year from endorsements, ahead of Messi on $27 million. Younger talents may be catching up and many of those can count on the World Cup to boost their own brands.
"The number of casual fans around the world that the World Cup touches does create a huge opportunity for these players to really build their brand," said Matt Hill, senior vice president for global sports consulting, at GMR Marketing in New York. "But it's the emerging stars that really stand to gain the most."
The battle on the pitch is matched by battles for followers on social media -- the biggest stars have hundreds of millions -- whom brands with little connection to soccer want to reach.
Messi probably doesn't drink a lot of Mongolian milk but Chinese dairy firm Mengniu is one of many willing to pay him to put his face on World Cup adverts. Argentina may win or lose, but Messi's "Natural Power" -- the slogan on that publicity campaign -- will go on well past this World Cup.
(Reporting by Alastair Macdonald, editing by Neil Robinson) ((firstname.lastname@example.org; +7 929 647 3308; Reuters Messaging: email@example.com))