Ricardo Carvalho hailed Cristiano Ronaldo as an "almost perfect" footballer who deserves to be named the best in the world for a third time.
Real Madrid winger Ronaldo won the Ballon d'Or in 2008 and 2013 and his Portugal teammate Carvalho believes the 29-year-old deserves to retain the award.
And he thinks that Ronaldo, who has scored 275 goals in 263 games for Real, is still getting better.
He said in a news conference: "I think he is the best. For us Portuguese, everyone is expecting that Cristiano can win the third Golden Ball.
"We are so proud of him. He is doing a great job during these past six or seven years. He is improving all the small details, making so many goals. He wants always more, even in training. Maybe next he can break his own records. He is looking always to try his best."
Ronaldo, who is Portugal's 52-goal record scorer, helped Real win their 10th Champions League this year, scoring a record 17 goals in a season in the competition, including one in the final against Atletico Madrid.
After scoring 51 goals for Real last season, he has begun the current campaign with 23 in just 17 games and Carvalho thinks it is hard to see how he could improve, adding: "It is difficult because when you see him, he is almost perfect, he is strong, good in the air, he is fit always. It is difficult to say what he is missing."
Ronaldo returns to Old Trafford, where he spent six years and won three Premier League titles and the Champions League as a United player, for Tuesday's friendly against Argentina. And Carvalho, who used to play alongside him for Real Madrid, added: "I am sure he is proud to be here and play again here."
The game pits Ronaldo against Lionel Messi, the two men often described as the best in the world, and the winners of the last six Ballons d'Or.
Veteran centre-back Carvalho, 36, will be part of a defence that faces the task of how to stop Messi. And the former Chelsea defender, who is now with Monaco, said: "We don't know exactly who is going to play but the most important thing is for us to defend as a team and as a block and whoever is the nearest player, you need to mark them.
"We all know how good Argentina were. They were finalists in the World Cup. They have players who can decide the match in the spur of the moment. We just have to keep our eyes open and do our best."