Barcelona fans went bonkers after seeing Frenkie de Jong play in defense during their pre-season El Clasico win over Real Madrid in Las Vegas on Saturday, July 23.The Dutchman came off the bench in the second half for Andreas Christensen and was seen playing in the back four instead of his usual habitat in midfield.This puzzled the club's supporters. However, the risk paid off as De Jong held on his own at the back against Real Madrid's marauding forwards and even started a few attacks.The 25-year-old has been the subject of transfer speculation this summer with multiple reports linking him to Manchester United.Erik ten Hag, their new manager, is keen to reunite with his former Ajax protege. The Red Devils are actively looking to reinforce their midfield following the departures of Paul Pogba and Juan Mata this summer as free agents.FC Barcelona@FCBarcelonaFULL TIME! #ElClásico 564557123FULL TIME! #ElClásico 🇺🇸 https://t.co/J2S3hIkY6kWhile Barcelona are reportedly looking to sell him to free up the club's finances, De Jong is keen to stay on at the Camp Nou. According to transfer expert Fabrizio Romano, the Catalans have reached an agreement with United for the midfielder for a deal worth €85 million.The Dutchman became a source of banter from some of the club's supporters following his exploits in the defense against Los Blancos. Some were of the opinion that he was even willing to revert to playing in defense in order to avoid joining United.One fan drew parallels with Javier Mascherano, a former Barcelona midfielder who later adapted to a more defensive role as a centre-back.Here are some of the best Twitter reactions to De Jong playing in defense:Bwogi@bwoginiusCommentator: Frenkie De Jong must be saying, "Please Xavi, I'm OKAY playing as a defender as long as you don't send me to Manchester United!" #ElClasico51Commentator: Frenkie De Jong must be saying, "Please Xavi, I'm OKAY playing as a defender as long as you don't send me to Manchester United!" 😥😥😂😂😂 #ElClasicoplfc@plfc15Is Xavi trying to turn De Jong into Mascherano or what? Why is this man playing as a defender 🤣🤣Is Xavi trying to turn De Jong into Mascherano or what? Why is this man playing as a defender 🤣🤣I am Negan@freakforbrunoFrenkie de Jong can be the greatest defender when he wants to be. Bring him in @ManUtd6Frenkie de Jong can be the greatest defender when he wants to be. Bring him in @ManUtdThe Iron Duke (Unruly) 💜🖤💙@ScelonGDe Jong: I rather play central defender than joining Manchester United 🤣🤣🤣🤣🤣🤣De Jong: I rather play central defender than joining Manchester United 🤣🤣🤣🤣🤣🤣hamyauns@codetillyoudropSergi Roberto as an attacking midfielder and De Jong as a defender. Interesting to say the least. #ElClasico1Sergi Roberto as an attacking midfielder and De Jong as a defender. Interesting to say the least. #ElClasicoDickson phillip@Dicksonphillip1De Jong playing as a central defender??? WTFDe Jong playing as a central defender??? WTFMax MUFC@maxmufc7Frankie De Jong is slowly getting the message from Barca. Isn’t an automatic starter, when he does play will be as central defender. All this to stay for champions league football in a World Cup year doesn’t make football sense. twitter.com/_adriansnchz/s…ᴀᴅʀɪᴀ́ɴ sᴀ́ɴᴄʜᴇᴢ@_AdrianSnchzSi Frenkie no entiende el mensaje…Más claro el agua. twitter.com/helenacondis/s…31Si Frenkie no entiende el mensaje…Más claro el agua. twitter.com/helenacondis/s…Frankie De Jong is slowly getting the message from Barca. Isn’t an automatic starter, when he does play will be as central defender. All this to stay for champions league football in a World Cup year doesn’t make football sense. twitter.com/_adriansnchz/s…DSamuel3@vacation_papiDe Jong playing at cb for Barca gives me mad Javier Mascherano vibes. If they keep him(which I hope they dont), I can see what Xavi could be planning.De Jong playing at cb for Barca gives me mad Javier Mascherano vibes. If they keep him(which I hope they dont), I can see what Xavi could be planning.PedriestaR💫@damzo_officialXavi is doing to De Jong what Pep did to Mascherano1Xavi is doing to De Jong what Pep did to MascheranoANDAH@AndahJnrWait, I don't understand Xavi again, why playing fdj from centre back, abi na me eyes dey pain?31Wait, I don't understand Xavi again, why playing fdj from centre back, abi na me eyes dey pain?Lula@lulajackie11Frenkie De Jong a lo Mascherano … como central Frenkie De Jong a lo Mascherano … como central 🔵🔴Barcelona's pre-season gathering paceThe Catalans beat arch-rivals Real Madrid 1-0 in Las Vegas on July 23 to make it two wins from two on their United States tour. They beat Inter Miami 6-0 in Fort Lauderdale last Tuesday, July 19.The El Clasico rivals played their A-teams, with Xavi's side getting the better of Real Madrid with their stoic defense. The defending Champions League winners failed to muster a single shot on target in the match.The game also saw Robert Lewandowski's debut play in Barca colors since the switch from Bayern Munich for a deal in the region of €50 million. While he didn't feature on the scoresheet, the Pole got forward well and threatened Real Madrid's defense.FC Barcelona@FCBarcelonaThings we love to see #ElClásico180881054Things we love to see 😍 #ElClásico https://t.co/S6X5XfNBi9Barcelona are looking in good shape and have three more pre-season games before the start of the new season. They will play Juventus on July 27 in Los Angeles followed by New York Red Bulls on July 31 in New Jersey. The Catalans will then return to their home turf to cap off their pre-season by facing Pumas UNAM on August 6.