Gerard Pique has named Cristiano Ronaldo, Didier Drogba and Robert Lewandowski as the toughest opponents he has faced in his career.
The Barcelona defender, a former team-mate of Ronaldo at Manchester United, admits the Real Madrid star has to be considered one of the very best players in the history of football.
Pique also praised Drogba - who faced him during his Chelsea career - for his pace and power, and revealed that Bayern Munich striker Lewandowski is supremely difficult to mark.
Asked to name his most formidable opponents, he told a video hosted by Unscriptd: "One of them was Drogba - one of the best strikers I have seen. He had everything. Pace, really strong, good in the air - he was amazing.
"The other one was Cristiano Ronaldo. I had to face him a lot of times and he's one of the best players in history. He's really complete, he knows how to score, assist, shoot free-kicks, penalties. He can do everything.
"Lewandowski is another. He's tall, can use both legs. It's really hard to mark this kind of player. You don't know what they will do."
Pique declined to choose team-mates Lionel Messi, Luis Suarez or Neymar given that he only has to face down Barca's formidable front three in training.
"Obviously I'm not saying Lionel Messi, Neymar, Luis Suarez, the ones I have to face every day in training, because you cannot see our 'battles'," he added.