On Sunday Manchester United will travel to Liverpool for their biggest match of their season. It will be a rip-roaring, full-bloodied battle which may well be settled by one moment of magic - an occasion made for those who shine on the biggest stages. And yet last year's Champions League man-of-the-match, a man who also played at the World Cup in Brazil, may well struggle to make Louis van Gaal's starting line-up. Angel di Maria has had a difficult start to life in a Manchester United shirt since arriving from Real Madrid . Di Maria (second right) has suffered a Fernando Torres-eque loss of form that nobody saw coming . Based on ability, Angel di Maria should be a shoo-in. His explosive pace and unnerving eye for a killer pass would seem to be the perfect fit for a 90 minutes in which United may well spend long periods on the back foot, looking to counter. But the skills that made Ed Woodward write Real Madrid a cheque for the best part of £60m have rarely been displayed after Di Maria suffered a Fernando Torres-esque loss of form that nobody saw coming. The promise of an explosive partnership down the left with fellow new boy Luke Shaw had United fans drooling. Louis van Gaal has stuck by his man so far, but he has a big decision to make ahead of Sunday's match . Manchester United travel to Liverpool, and Di Maria may not be in the starting line-up at Anfield . Di Maria, however, did not want to leave Madrid and that is where the problems began. Then came the weather. Mancunian winters, as Roy Keane pointed out, can be hard to endure for those used to sunnier climes. Six hours of grey light a day and continual rain can hammer at the mindset of those not used to it. Di Maria also struggled to adapt to Louis van Gaal's tactical switches. He is not alone in that, and has rarely been given licence to roam up and down the left wing. The problems for Di Maria began when he left Madrid - he was happy there and did not want to leave . Di Maria was sent off in Manchester United's FA Cup clash with Arsenal earlier in March . Van Gaal pointed out that most players do not find their feet until their second season - but try telling that to Chelsea fans who have seen Diego Costa fit seemlessly into Jose Mourinho's Premier League leaders. As if the above were enough to contend with, then came the break-in. Sat at home in a foreign country watching TV with your wife and young daughter when suddenly a quiet night in is interrupted by the terrifying sound of raiders armed with scaffolding poles trying to smash their way into your isolated house. Juan Mata started for Manchester United in Di Maria's absence against Tottenham and impressed throughout . Van Gaal now has to decide whether to stick or twist - Mata (centre) or Di Maria (right) on Sunday? Yes, the thugs were disturbed by the alarm system and made their getaway. But the trauma of that experience must remain. There may have been, and may still be, recurring nightmares. In a state of panic, the Di Marias fled to a city centre hotel with a security team. The family now live high above the ground at a separate city centre apartment. It is safe and it is luxurious but it may well feel like a prison and is not the ideal environment in which to raise a young child. Van Gaal, a family man, knows this. He has given Di Maria compassionate leave and stood by his man after the latest low, a red card for grabbing referee Michael Oliver's shirt in the FA Cup defeat to Arsenal. Di Maria has shown flashes of his potential, scoring four goals in United colours since his arrival in August . Di Maria (right) was all smiles on international duty in September, but his form has been poor for United . In the subsequent victory over Tottenham, for which Di Maria was suspended, United delivered their best 45 minutes of the season. Replacement Juan Mata linked well with Ander Herrera as Van Gaal's side displayed a synchronicity rarely seen this season. The Dutchman now has to decide whether to stick or twist. Mata, for all his qualities, lacks pace. Di Maria is a better player but can he finally deliver when United need him most? With £60m already spent it is a gamble worth taking.
Manchester United travel to Liverpool for a huge game on Sunday . Louis van Gaal has to decide whether to start out-of-form Angel di Maria . Di Maria has had a difficult start to life in Manchester, particularly after intruders broke into his house while he and his family were there . Based on ability, Di Maria should be in the starting XI, but Van Gaal may decide to start Juan Mata instead of the Argentinian . CLICK HERE for all the latest Manchester United news .