The 2021-22 season is off to a cracking start as the action heats up across Europe's top five leagues. Several world-class players have continued their merry ways this season, scoring goals and providing assists for fun.The likes of Cristiano Ronaldo and Robert Lewandowski have continued their ridiculous goalscoring form over the past few seasons. However, several top talents have failed to perform at an elite level for quite some time. That raises questions about their long-term future at their respective clubs.On that note, here's a look at the five world-class players who are well past their prime:#5 Mesut OzilMesut Ozil is currently plying his trade at Fenerbahce.Mesut Ozil is considered by many to be one of the greatest playmakers in modern football, and it is difficult to argue against that.In his prime, the former German international was a magician with the ball at his feet, notching up countless assists for a misfiring Gunners outfit. However, Ozil was treated somewhat unfairly by his former teammate Mikel Arteta, and the duo had a well-documented fallout.The now-33-year old was frozen out of the first team by Arteta, and was forced to train with the reserves.UEFA.com DE@UEFAcom_de#OnThisDay in 2⃣0⃣1⃣6⃣🌪️⚡️🤯 @MesutOzil1088 🆚 Ludogorets ⚽️🎯💪#UCL | @Arsenal1:44 AM · Nov 1, 20217757495#OnThisDay in 2⃣0⃣1⃣6⃣🌪️⚡️🤯 @MesutOzil1088 🆚 Ludogorets ⚽️🎯💪#UCL | @Arsenal https://t.co/nzQUgmJJbTOzil was also left out of Arsenal's Premier League and Europa League squads for the 2020-21 season. It would be fair to say that the German has spent the last few of his best footballing years on the sidelines at the Emirates.The 33-year old is currently plying his trade in the Super Lig for Turkish powerhouse Fenerbahce SK.#4 IscoIsco has been named only twice in Real Madrid's starting XI this season.At 29, Isco is supposed to be at the peak of his footballing powers, but the Spanish international has failed to live up to his immense potential.Isco enjoyed his breakthrough spell at Malaga, where he established himself as one of the most talented players of his generation. Real Madrid paid £27 million to acquire Isco's services in the summer of 2013, and his incredible talent was lauded by fans and critics alike.Fabrizio Romano@Fabrizio_RonamoOFFICIAL. Confirmed. Isco Alarcón joins AC Milan on a permanent move from Real Madrid. €25m guaranteed plus add ons. Contract until June 2027.🔴⚫️🤝 #ACM #SempreMilan Isco wanted to leave Real Madrid now… and the deal is official. Here we go confirmed.2:07 AM · Nov 2, 2021772107OFFICIAL. Confirmed. Isco Alarcón joins AC Milan on a permanent move from Real Madrid. €25m guaranteed plus add ons. Contract until June 2027.🔴⚫️🤝 #ACM #SempreMilan Isco wanted to leave Real Madrid now… and the deal is official. Here we go confirmed. https://t.co/HGIQ6fiJ52He was also tipped to be the man to lead Spanish football after the golden generation passed on the baton. But Isco has severely underwhelmed in national and club colours.The attacking midfielder has registered a meagre six appearances for Real Madrid this season. Four of them have been from the bench. Isco certainly has the talent to turn things around, but one would argue that the Spaniard is likely well past his prime.