Midfielders are arguably the hardest-working players in a team, as they provide a key link between attack and defense.Like other positions on the field, there are various types of midfielders like box-to-box, central, defensive, attacking, and so on. Midfield is the place where games are often decided, so it is paramount that teams contending for titles have quality personnel in this key area of the field.Over the years, a plethora of talented midfielders have graced the game, delivering big titles after big-money moves. On that note, here's a look at the five most expensive midfielders in the history of the game:#5 Zinedine Zidane - €77.5 millionZinedine ZidaneArguably one of the best players to have graced the game, Zinedine Zidane arrived at Real Madrid in the summer of 2001 and proved to be an instant hit.Zizou, as he was affectionately known, endeared himself to the Madrid faithful by scoring a stunning winner against Bayer Leverkusen to help the Merengues win their third Champions League title in five years.😱 Zinédine Zidane's spectacular volley in the 2002 final! 🚀🎯The first time he lifted the #UCL 🏆... https://t.co/MMuICEBvP7 pic.twitter.com/MQGarfsUuh— UEFA Champions League (@ChampionsLeague) July 9, 2019The Frenchman wasn't a prolific scorer, netting only 49 times in over 200 appearances, but provided a staggering 68 assists. The 1998 Ballon d'Or winner was one of the few players who picked himself in a star-studded Madrid squad.A decade later, Zidane would help his former club win an unprecedented Champions League three-peat and deliver two La Liga titles across two managerial stints.#4 Kai Havertz - €80 millionKai HavertzKai Havertz is one of the best young midfielders in the game at the moment. He arrived at Stamford Bridge with much fanfare in the summer of 2020 after Chelsea splurged the cash to land the precocious midfielder.Although Havertz took his time to get going under Frank Lampard, the 22-year-old flourished in a more advanced role under his compatriot Thomas Tuchel. The former Bayer Leverkusen midfielder scored the only goal of the game in the Champions League final against Manchester City as Chelsea won the competition for the second time in nine years.Kai Havertz scores his first EVER Champions League goal! 🔥#UCL #UCLfinal pic.twitter.com/973uFNXRXY— Goal (@goal) May 29, 2021Earlier, Havertz had a prolific 2019-20 campaign with Leverkusen, scoring 18 goals across competitions. The midfielder has also dazzled in German colors, scoring five goals, two of them at Euro 2020, and registering nine assists in only 18 games.