#4 Most Appearances in UEFA Competitions
Iker Casillas, currently at Porto, has the all time leading appearances in UEFA Club Competitions, with 178 appearances. Ronaldo has 161 appearances in total, while Messi is trailing at 129 appearances. Ronaldo is actually joint 6th in the list of all time appearances, while Messi is (surprise, surprise) joint 35th in the all-time UEFA Club Competitions appearances.
In Champions League, however, Ronaldo has the second most appearances – 157, while Messi on 125 is joint 12th. Casillas is still a little ahead of those two with 171 appearances. With Porto appearing in the Champions League this season, it is impossible for Ronaldo to match up to Casillas by this year, so the records shall remain intact for another season, at least. Ahead of that though, there isn't much guarantee.