The Portugal international has had a shocking season with only four league goals to his name.
His poor form has come hand-in-hand with Real Madrid sitting precariously in fourth place in the La Liga table.
Meanwhile, Messi is enjoying unrivalled success and continuing to flourish at the Nou Camp.
But according to Spanish outlet Diario Gol, Ronaldo has a number of key reasons to be angry with his arch-rival.
The first is because Barcelona are nine points clear at the top of the table.
That means if they remain ahead by that many points by the time the El Clasico comes around on May 6 then they will already be crowned champions.
And with that Ronaldo would have to form a guard of honour for Messi and his team-mates as they take to the pitch.
Diario Gol add that the 33-year-old is also worried of Barcelona’s dominance in the Champions League.
The striker apparently fears that only Manchester City would be able to stop Ernesto Valverde’s side but it looks likely Messi will help the Catalan club secure the prestigious trophy.
To make matters worse, by winning the league title and Champions League Messi would be likely to claim the Ballon d’Or at the end of the year.
Finally, because Real are still battling for the Champions League places in the league, Ronaldo thinks he will have to give his maximum all the way to the end of the season, which could burn him out for the World Cup.
On the other hand, Messi could be rested for the final few matches and head to Russia fresh.