#3 Sergio Ramos
Real Madrid have lost arguably their most valuable asset in the ongoing summer transfer window and one of the most decorated players in Champions League history.
Sergio Ramos has played a pivot role in every team he has represented, winning every major club and international trophy on offer. The Spaniard is not only one of the best defenders in world football in the 21st century, but he's also an exceptional leader who always leads by example, especially in big games.
Despite his reputation of picking up red cards, Ramos has stepped to the fore time and again in big matches. He has scored seven goals in the Champions League knockout stages, the most by any defender.
That includes a goal apiece in the 2014 and 2016 Champions League finals against Real Madrid's cross-town rivals Atletico Madrid. Ramos scored the all-important equaliser in added time, courtesy a towering header in the 2014 CL final, while he opened the scoring in the 2016 title match.
#2 Lionel Messi
Lionel Messi is Barcelona's greatest player of the 21st century and arguably their best-ever in 121 years of history.
But Messi has left Barcelona this summer after an illustrious 17-season career, where he won 35 trophies. This incredible trophy haul includes four Champions League trophies.
La Pulga has been one of the most prolific goalscorers in the Champions League era and finds himself in second place in the competition's all-time goalscoring charts. Messi has notched up 120 goals from 149 appearances in the tournament.
The six-time Ballon d'Or winner has produced some of the Champions League's greatest moments. Messi dummied one of the best defenders in world football at the time, Jerome Boateng, who twisted and tumbled onto the floor, while Messi chipped the ball over the best goalkeeper at the time, Manuel Neuer.
The Argentine also put on a masterclass against Manchester United at the Wembley Stadium in the 2011 Champions League final to score his first goal on English soil.
#1 Cristiano Ronaldo
Cristiano Ronaldo is unquestionably the greatest-ever player in the history of the Champions League.
The five-time Ballon d'Or winner holds almost every major record in the Champions League. Ronaldo has the record for most Champions League goals (134), most appearances in the competition's knockout stage (34), most hat-tricks (8), highest goalscorer in CL finals (4), and the only player to score in three CL finals.
The Portuguese superstar is also the only player to score for two winning teams in the final, the only one to score in 11 successive games, the only one to score in all six group-stage matches in a season, and the list goes on and on.
Cristiano Ronaldo has racked up an incredible tally of 134 goals and 40 assists in just 176 appearances in the Champions League proper (group stage to final). The 36-year-old has laid his hands on five Champions League trophies at two different clubs.
Ronaldo was a key figure in Manchester United's Premier League and Champions League double in 2007-08. He would go on to win four more Champions League titles in the span of five years in Real Madrid colours.