The summer transfer window is one of the biggest events in the global football calendar. The Covid-19 pandemic might have brought football leagues across the world to a standstill but clubs are already plotting their moves for summer transfer business.There have already been several high-profile transfers in the year 2020. Jesse March's Red Bull Salzburg has been raided by both Liverpool for Takumi Minamino and Borussia Dortmund for Erling Braut Haaland. Zlatan Ibrahimovic has moved back to AC Milan from LA Galaxy.#ACMilan forward Zlatan Ibrahimovic will reportedly return in time to face #Lazio and #Juventus in #SerieA. https://t.co/epox4Ak6tH pic.twitter.com/jPAbGgnkhA— footballitalia (@footballitalia) June 5, 2020With the transfer window to open up soon, there is no doubt that the summer transfer window will see some elite players changing employers as clubs look to get reinforcement before the 2020-21 season starts. Here is a list of top five transfers that could happen this summer.#5 Miralem Pjanic | Juventus > Barcelona Miralem Pjanic could be on his way to Barcelona this summer.The Bosnian midfielder will be one of the top summer transfer targets for Spanish giants Barcelona. Miralem Pjanic is one of the highest paid players at the Bianconeri in terms of wages. Juventus have been facing financial issues and want to off-load the midfielder to a club that can match his pricetag of €60 million.💥 If Miralem Pjanić leaves Juventus, he wants to play for Barcelona. He rejected an offer from PSG and he's not interested in Chelsea either. If Pjanić doesn't join Barça, he will stay at Juventus for next season [tuttosport] pic.twitter.com/trb8V45pMH— FCBarcelonaFl #StayHome 🏡 (@FCBarcelonaFl) June 7, 2020Barcelona have been in conversation with the Italian giants and according to recent reports in Italy, they are moving closer to completing an agreement with the player. The 30-year-old has his mind dead set on playing for Barcelona and has already snubbed Chelsea, and French champions Paris Saint-Germain for a possible move to the 2018-2019 Spanish champions.#4 Kai Havertz | Bayer Leverkusen > Real MadridKai Havertz has drawn a lot of interest from big clubs and Real Madrid look strong to acquire him.Due to his recent performances, Kai Havertz has quickly turned into one of the hottest transfer targets for elite clubs across Europe. The player from Bayer Leverkusen has set the Bundesliga ablaze his stunning performances, recently he became the first player to score 35 Bundesliga goals before turning 21. Real Madrid wants to add the youngster to their ranks and Zinedine Zidane's side would certainly benefit hugely with his arrival.Leverkusen have rejected a €80m offer from Real Madrid for Kai Havertz, including an immediate loan back to Leverkusen for one year. Bayer 04 will not accept anything below €100m [Bild] pic.twitter.com/zBK4BKbu3R— Bayern & Germany (@iMiaSanMia) June 4, 2020According to reports from the German and Spanish media, Real Madrid have already made a €71 million transfer bid for the player. As per the reports, the Spanish have also agreed to loan the player back to Bayer Leverkusen for the 2020/21 season to sweeten the deal.#3 Kalidou Koulibaly | Napoli > Manchester UnitedManchester United want Kalidou Koulibaly to form a possible partnership with Harry MaguireManchester United have been chasing Kalidou Koulibaly for a long while now and it seems that their wishes could finally be fulfilled, as reports indicate that they could acquire the Senegalese defender this summer. Koulibaly has been a pillar for Napoli's defensive line-up ever since he moved there back in 2014. The Italian club have set a price-tag of €100 million on the defender and it would be interesting to see whether Manchester United will be able to match that with a suitable bid.Manchester United's hopes of signing Kalidou Koulibaly in a cut-price deal have been crushed after Napoli chief Cristiano Giuntoli insisted the club's valuation of their player will not change after the coronavirus crisis.#TheBestInTheBiz#SportsJagaban#napolitano #Koulibaly pic.twitter.com/NliU9zZqMP— Oga Sammy (@wejinyasam) June 8, 2020The negotiations between the two clubs have not reached any conclusion as of yet as Napoli has refused to budge from their asking price of €100 million for their star defender. The Italian club have previously turned down a €91 million bid from the Red Devils. Manchester United have been eager to get a world-class central defender for a while now and there is no doubt that Kalidou Koulibaly would be the perfect fit in that role.#2 Jadon Sancho | Borussia Dortmund > Manchester UnitedJadon Sancho seems to be the next in the list of players poached from Borussia DortmundManchester United want to solidify their attacking line-up and after completing Odion Ighalo's loan extension it seems they have turned their focus on Jadon Sancho. The England youngster is one of the best players in his position and United are keen on signing the player as soon as possible. 📋 Jadon Sancho is expected to play on the right of a forward three if he moves to #mufc this summer. [via MEN] pic.twitter.com/a9DR8v06PJ— United News Hub (@UnitedNewsHub) June 8, 2020The Borussia Dortmnund midfielder will be one of the hottest transfer prospects in the upcoming transfer window. The German club have set the midfielder's price tag at €130 million, however, Manchester United have been in negotiations with the German club to reach a suitable price that could satisfy both parties and the player.As Dortmund braces for Sancho's departure after three hugely successful years at the Westfalenstadion, the Bundesliga side have no plans to cut any deals as economic pressure mounts on football clubs due to the worldwide pandemic.#1 Lautaro Martinez | Inter Milan > BarcelonaEl Toro Martinez wants a move to Barcelona to play alongside Lionel Messi'El Toro' Lautaro Martinez is the talk of the town currently, the Argentine has been in high demand and Barcelona are the frontrunners in the race to acquire his signature. The Blaugrana have been desperate to get Martinez and have been going back and forth with Inter Milan in their negotiations for the striker.Lautaro Martínez has told Barcelona he only wants to leave if it's for Barça. Negotiations are still ongoing. [md] pic.twitter.com/hkJeunISSd— barcacentre (from 🏡) (@barcacentre) June 2, 2020Inter Milan do not want to sell their star striker for anything less than €110 million and Barcelona have been trying to convince Inter Milan to let go of their player for a deal including Firpo Junior + €70 million.Barcelona believe Lautaro Martinez is the perfect replacement for the aging Luiz Suarez. The Argentine has scored sixteen goals in all competitions for Inter Milan this season. Martinez alongside Belgian striker Lukaku, has formed one of the most deadly strike partnership in all of Europe.