Some Manchester United fans have ditched Cristiano Ronaldo for Lionel Messi in the Greatest of All Time debate after it emerged that the Portuguese wants to leave the Red Devils.Ronaldo became a fan favorite during his first stint with the Old Trafford outfit under then-manager Sir Alex Ferguson. He remained in the supporters' good books despite leaving the club for Real Madrid in the summer of 2009.The 37-year-old then sealed a sensational return to Manchester United last summer, leaving fans delighted. He picked up right where he left off as he scored 24 goals and provided three assists from 38 matches in all competitions last term.However, Manchester United failed to secure UEFA Champions League qualification, finishing sixth in the Premier League table. This has led to speculation over Ronaldo's future at Old Trafford this summer.It emerged on Saturday that the Portugal international has asked the Red Devils to let him leave if they receive a satisfactory offer this summer. The news has not gone down well among a section of the club's supporters.Fans have taken to social media to express their frustration with the forward, while a few have gone on to admit that Paris Saint-Germain superstar Messi is better than him. Here are some of the best Tweets on the same:Trey@UTDTreyLionel Messi is the GOAT575596575Lionel Messi is the GOATUTDJadon@UTDjedonImagine being a Football fan and not admitting that Messi is the GOAT.I'm sorry as being United Stan couldn't let me just admit it 2208171Imagine being a Football fan and not admitting that Messi is the GOAT.I'm sorry as being United Stan couldn't let me just admit it 😔 https://t.co/7kfSOpnqoiDestiny A. Eneluwe@Edcdestiny1@UTDjedon Die hard utd fan, but Messi is the GOAT.33@UTDjedon Die hard utd fan, but Messi is the GOAT.frankthenailtech@Frank_nails@UTDjedon I am a united fan but Messi is the G.O.A.T74@UTDjedon I am a united fan but Messi is the G.O.A.TOne fan wrote on Twitter:"Messi is GOAT. Another one bitest the dust. Penaldific is like a gold digger who takes United fans for a ride."Cracker Jaker@Cracker_Jaker@UTDjedon Messi is GOAT.Another one bites the dust.Penaldific is like a gold digger who takes United fans for a ride..8@UTDjedon Messi is GOAT.Another one bites the dust.Penaldific is like a gold digger who takes United fans for a ride..𝕽𝖚𝖙𝖙ø@ezrandez@UTDTrey This is why Messi is the greatest football player of all time10367@UTDTrey This is why Messi is the greatest football player of all time𝐌𝐚𝐥𝐢𝐤 ✨@_Just_Malik@UTDTrey At the end of the day, we all know the truth683@UTDTrey At the end of the day, we all know the truthkingmike@KingmikeA1UTD@UTDTrey We been knew this92@UTDTrey We been knew thisRecent claims have put Ronaldo's future at Old Trafford up in the air. Napoli are reportedly interested in signing the five-time Ballon d'Or winner, while Chelsea and Bayern Munich are aware of his situation.However, Manchester United are determined to retain the forward's services beyond this summer. Erik ten Hag's side maintain that the player is not for sale during the ongoing transfer window.Manchester United's Ronaldo and PSG's Messi continue to dominate GOAT debatesThe two forwards have been at the top of their games for almost two decades now. While they are both heading towards the end of their careers, they continue to dominate the Greatest of All Time debates in football.It is worth noting that the two have won 12 Ballon d'Or awards between them so far. Real Madrid midfielder Luka Modric is the only player to win the accolade apart from them since 2008.