Opposition boss: Rafael Benitez has had many clashes with the boss in the past during his Liverpool days and famously delivered what became known as 'Rafa's rant' at a press conference when he criticised the Scot and United. The Spaniard forged his reputation at Valencia and has also coached Inter Milan but his appointment as 'interim' manager at Stamford Bridge met with disapproval from a large section of the club's support. Nonetheless, he is a shrewd tactician who will be looking to get one over the Reds again at the Theatre of Dreams.
Star man: Juan Mata has enjoyed a fabulous season and is going from strength to strength in the Premier League. The astute acquisition from Valencia actually started his career in Real Madrid's B team and is a mainstay of the Spain squad. The 24-year-old has twice scored in games against United and looks certain to be a major threat again at the weekend.
Quote/unquote: "I think it’s difficult [for United] when you’ve been knocked out of an amazing competition like the Champions League. Your confidence is not the same. The happiness inside your heart is not the same." Chelsea's David Luiz.
Sub-plots: All eyes will be on Old Trafford again to see how the Reds react to the midweek disappointment. Any head-to-head between Sir Alex and Rafa Benitez attracts attention and the team selection will be analysed - particularly as far as Wayne Rooney is concerned. Primarily, of course, it's all about getting through to the semi-finals and setting up another trip to Wembley.
Whistle-blower: Howard Webb is the man in the middle. The World Cup final referee also took charge for this season's 3-0 triumph at Newcastle and 2-1 home success against Liverpool.
Rivals watch: The other FA Cup quarter-finals see Everton entertain Wigan, Manchester City face Barnsley and Blackburn travel to Millwall. Both last-four fixtures will take place at Wembley.