2021 has been a rollercoaster year for world football.As we enter the last two months of the year, it is worth taking a moment to look back and reflect upon the historic moments of the year.At club level, viewers saw Chelsea lift the UEFA Champions League once again after a nine-year wait.On the international stage, we witnessed the Italian national team come out triumphant in the UEFA Euro 2020 tournament. This year, we also saw several top players hang their boots up after vastly successful careers.Let's take a look at five high-profile players who retired this year.#5. Wes Morgan - Leicester CityManchester United v Leicester City - Premier LeagueWes Morgan will have a place in the hearts of Leicester City fans forever.The Jamaican enjoyed a successful career before his eventual retirement earlier this year. Originally from Nottingham Forest, Morgan represented The Reds for ten years before signing for Leicester in 2012.His spell with Leicester was successful; and will mostly fondly be remembered for The Foxes' astonishing achievement in 2016.Sky Sports Retro@SkySportsRetroWes Morgan after winning the Premier League with Leicester.11:29 AM · May 21, 202119917Wes Morgan after winning the Premier League with Leicester. https://t.co/THFUeGqVwUCaptaining the side, Morgan went on to lead Leicester to an unprecedented Premier League title. In a result that was beyond anyone's expectations, Leicester City defied all odds to go on and lift the title.Leicester City@LCFCOur Premier League-winning captain Wes Morgan will retire at the end of season after nine hugely successful years at the Club and a career spanning over 750 professional games 💙#ThankYouWes3:30 AM · May 21, 2021420643335Our Premier League-winning captain Wes Morgan will retire at the end of season after nine hugely successful years at the Club and a career spanning over 750 professional games 💙#ThankYouWesSince then, the feat has been described as a 'sporting miracle', the kind that happens only once in a millennium. Morgan topped off an incredible career in style: he won the FA Cup with Leicester this year, beating Chelsea 1-0 to the prize.The defender certainly has a place in Leicester's history books and will fondly be remembered by the Foxes' fans for a long time.#4. Antonio Valencia - Manchester UnitedBlackburn Rovers v Manchester United - Premier LeagueAntonio Valencia is one of the most successful defenders of his generation.The Ecuadorian enjoyed a career across many countries. Having represented the likes of Villareal and Wigan Athletic, his most prolific stint was at Manchester United in the Premier League.Squawka Football@SquawkaAntonio Valencia was the first non-European player to make 300 appearances for Manchester United.🏆🏆🏆 Community Shield🏆🏆 Premier League🏆🏆 League Cup🏆 Europa League🏆 FA CupEnjoy retirement.10:45 AM · May 12, 20211484281Antonio Valencia was the first non-European player to make 300 appearances for Manchester United.🏆🏆🏆 Community Shield🏆🏆 Premier League🏆🏆 League Cup🏆 Europa League🏆 FA CupEnjoy retirement. https://t.co/XozAHfHQ6zOperating as a right-back, Valencia went on to represent the Red Devils for ten years. His outstanding career with the club was topped off by being awarded the captaincy during his final season.Valencia won several trophies with Manchester United. He won two Premier League titles, two EFL Cups, one UEFA Europa League and one FA Cup. He is one of the most successful players in Ecuadorian history.UEFA Europa League@EuropaLeague🇪🇨 Happy retirement, Antonio Valencia! 🔴🏆2⃣0⃣1⃣7⃣#UEL7:44 AM · May 13, 20213856303🇪🇨 Happy retirement, Antonio Valencia! 🔴🏆2⃣0⃣1⃣7⃣#UEL https://t.co/yYQSh83HvoValencia has also made 99 appearances for the national team. He left Manchester United in 2019 to return home to the Ecuadorian Football League. He announced his retirement from professional football in May 2021.