Manchester United host Liverpool at Old Trafford in the Premier League on Sunday as the 2020-21 season enters its last five games.A massive 13 points separate the two teams in the league table, with the Red Devils on course to finish ahead of their Northwest rivals for the first time in three years.While Manchester United have recovered from a poor start to the campaign, Liverpool's season has gone completely off the boil since the turn of the year, so much so that even their Champions League hopes are now hanging in the balance.The defending champions are sixth in the league table, four points off fourth-placed Chelsea, after drawing their last two games. Liverpool now face an uphill battle in a fixture they usually struggle with, especially at Old Trafford.Michael Oliver will referee Manchester United vs Liverpool on Sunday. Paul Tierney is on VAR duty. #awlfc [pl] pic.twitter.com/EFqH3a7tgT— Anfield Watch (@AnfieldWatch) April 27, 2021Meanwhile, Manchester United couldn't keep up with runaway leaders Manchester City but are on course for a strong finish to their campaign. They also have one foot in the 2021 Europa League final.Ahead of this mouth-watering game, let's have a look at how Liverpool and Manchester United would stack up in a hypothetical combined XI:Goalkeeper: Alisson (Liverpool)Alisson has made a few mistakes but remains Liverpool's undisputed choice in goal.It hasn't been his best season by any stretch of imagination, but Liverpool custodian Alisson gets into our hypothetical combined XI. That's because Manchester United have constantly swapped between Dean Henderson and David de Gea this season, and neither has been truly convincing between the sticks.Proud to support my country 🇧🇷 to fight #COVID19 & donate to @thewhof Give A Breath to Health campaign to deliver oxygen & other supplies for patients & #healthworkers in need. Please join me & donate here: https://t.co/hjv2pTdQKj Thank you, @WHO! Together, for #HealthEquity!— Alisson Becker (@Alissonbecker) April 8, 2021Alisson, meanwhile, has continued to be Liverpool's undisputed choice in goal. The 28-year old has managed only seven clean sheets this campaign but has produced moments of class in some tense moments, making jaw-dropping saves and helping Liverpool build from the back.