During the Premier League era, the great divide between Manchester United and Liverpool is one few players have dared cross.  The two sides from the North-west are the most decorated clubs in the country and the rivalry between them has only intensified over the years.  Once you have picked your side, there should be no going back. In fact, no first-team player has transferred directly between the clubs since Phil Chisnall’s move from United to Liverpool back in 1964.Gabriel Heinze ignored this unwritten rule and famously attempted to follow in Chisnall’s footsteps in 2007, only for Sir Alex Ferguson to put his foot down.“I can assure you, Liverpool will not be getting Gabriel Heinze,” Ferguson said. We can put that to bed right now and we have done so.”Despite Heinze taking his dispute to a Premier League arbitration panel in an attempt to force the deal through, Ferguson was right. The former Argentina international was shipped off to Real Madrid instead.He may not have completed the move to Anfield but United fans certainly didn’t forgive and forget. On Heinze’s return to Old Trafford with Marseille in 2011, loud chants of ‘You Scouse bastard’ were aimed at him.Playing, or even wanting to play, for both United and Liverpool will make you public enemy No.1 in one of those cities. Just ask Michael Owen.READ: Michael Owen at Man Utd: Worth it just for *that* derby winnerBut Liverpool academy graduate Ethan Ennis has still decided to take the treacherous and rarely trodden path from Anfield to Old Trafford.Born in Runcorn, Ennis joined Liverpool’s academy at a young age and worked his way through their youth system. The attacking midfielder soon started to catch people’s attention due to his eye for goal, impressive dribbling ability and brilliant passing range. He marked his first start for Liverpool’s Under-18s with a goal against Sunderland in October 2020, cutting inside on his right foot before curling a fine shot past the goalkeeper. Ennis continued to impress and was rewarded with his debut in the prestigious FA Youth Cup, coming off the bench in their third-round clash against Sutton United in March 2021.With 64 minutes on the clock, Ennis had less than half an hour to showcase his talents. Fortunately for him, that was more than enough time.Six minutes after entering the pitch, he rose highest to nod James Norris’ cross into the back of the net, making it 4-0 to Liverpool. The teenager was then in the right place at the right time to grab his second goal of the game in the 82nd minute but decided to save his best til last.Picking up the ball just outside the penalty area, Ennis drove forward and danced through a host of Sutton defenders before cooly rolling the ball past the goalkeeper. A perfect hat-trick in the space of 15 minutes. Not bad at all.From a header to a poacher’s finish and then a brilliant solo goal, the three strikes against Sutton also showed Ennis’ wide range of talents.“Ethan is an Under-16 player and it was a great evening for him,” Liverpool coach Marc Bridge-Wilkinson told their official website after the game. “It was his debut in the FA Youth Cup and he got three goals!“What a wonderful achievement for him and he went on and did what I ask our subs to do: have an impact on the game. He arrived in great areas which forward players do and his finishing was really good.”Despite his exploits with the Under-18s, Liverpool refused to rush his progress and allowed him to drop back down to the Under-16.Unsurprisingly, Ennis quickly proved that he is far too good for that level. He tried to make things difficult for himself by taking on an entire defence but still found the back of the net, humiliating his helpless opponents in the process.Ethan Ennis goal for the U16s pic.twitter.com/35X5YPWJW3— 9 (@F9Txrres) March 27, 2021The 16-year-old looked set for a bright future at Anfield and was tipped to follow in the footsteps of homegrown talents Trent Alexander-Arnold and Curtis Jones. But he rejected a scholarship offer from Liverpool, putting other top academies on red alert.Despite holding talks with Chelsea and visiting their Cobham training ground earlier this summer, Ennis ultimately decided to join Liverpool’s arch-rivals.“I am delighted to announce that I have signed for Manchester United,” Ennis wrote on Instagram. “Grateful for this opportunity, can’t wait to get started.”If losing the highly-rated player wasn’t bad enough, seeing him hold a United shirt at Old Trafford just rubbed salt into Liverpool’s wounds.The Reds are now owed a development fee for Ennis, which could be decided by a tribunal if the two clubs fail to reach an agreement. But United won’t care, they’re still celebrating the fact that they managed to steal him from Liverpool’s clutches.Official: Ethan Ennis has signed for #mufc from Liverpool pic.twitter.com/mCdO5GKa0b— utdreport Academy (@utdreportAcad) July 27, 2021The United academy has been stockpiling the best young talent in recent years, signing the likes of Charlie McNeill from Manchester City and Joe Hugill from Sunderland. Ennis is the latest addition to that star-studded Under-18s squad and will be hoping to make an immediate impact when the new season gets underway.While there is still a long way to go and a lot of different factors to consider, the midfielder undoubtedly has the natural talent to one day play for United’s first team.Born two months after Wayne Rooney marked his United debut with a hat-trick against Fenerbache, Ennis could eventually become another adopted Mancunian.If he does become a United regular, it’s pretty safe to assume that he’ll get a rather frosty reception on his return to Anfield.By Nathan EgertonPL defenders beware: Man Utd cant hold Joe Hugill back for much longerWhere are they now? 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