Cristiano Ronaldo appears to be growing out his goatee to troll his biggest rival at the World Cup

AP Photo/Matthias Schrader

Cristiano Ronaldo and Lionel Messi have been battling for the title of "Best Footballer on the Planet" for almost a decade, but at the World Cup, it appears Ronaldo is growing out his goatee to prove he's the real "GOAT."

• Cristiano Ronaldo and Lionel Messi both have claims to be considered the "Greatest of All Time" or "GOAT."
• Ronaldo has recently taken the debate to another level, growing out a less-than-perfect goatee on his usually clean-shaven face to make the point.
• Ronaldo's play has backed up his statement, with a World Cup leading four goals already coming off his foot.

For the past ten years, the best player on the planet was either Cristiano Ronaldo or Lionel Messi.

But at the 2018 World Cup, it appears that Ronaldo is looking to end the debate, and he's trolling Messi with his facial hair as a part of his campaign.

It all started with Ronaldo's celebration after netting a hat trick against Spain to single-handedly carry Portugal to a 3-3 draw with the world powerhouse. After scoring one of his goals, Ronaldo celebrated by stroking his chin - a message many understood as Ronaldo claiming that he is the greatest of all time or "GOAT."

The display from Ronaldo is particularly intriguing when one considers that Adidas is currently running an ad campaign featuring Messi promoted with an actual goat to make the same argument.

Then, the notoriously clean-shaven Ronaldo doubled down on his claim by growing out his actual goatee ahead of Portugal's second match at the World Cup, taking his troll of Messi to a new level.

Across Twitter, eagle-eyed fans and reporters noticed the slight and could not look away.

Ronaldo's claim may be bold, but he's backing it up in style. After his hat trick in the opening match, Ronaldo scored again against Morocco to carry his country to a 1-0 win and a spot atop Group B.

Messi meanwhile, is left with some work to do - his only World Cup appearance so far has seen him missing a penalty kick that left Argentina to settle for a draw against an Iceland side that should have been far overmatched. Should Messi want to take back his claim as the GOAT, he'll have to show off his brilliance once again.

Thankfully, there's plenty more matches left to be played.

More World Cup 2018:

• The most mesmerizing photos from the World Cup so far
• World Cup Power Ranking: Where every team stands after one week at Russia 2018
• Senegal scored one of the most controversial goals of the World Cup when a player ran back onto a wide-open field after an injury

• A Russian city reportedly ran out of beer due to Swedish fans celebrating their first World Cup win in 12 years

  Iceland's goalkeeper directed a Coca-Cola commercial for the World Cup and made brilliant use of the country's 'SKOL' rallying cry