Real Madrid host Manchester United in the first leg of an eagerly-anticipated UEFA Champions League last-16 encounter.
Two European heavyweights - with 12 continental crowns between them - will square off in the Spanish capital in a game which has captured the imagination of a global sporting audience.
Real are the most successful side in the history of the European Cup, but have gone 11 years since they last lifted the trophy and will be determined to end that barren run in 2013.
Jose Mourinho's men have been forced to make the Champions League their top priority this season, with domestic struggles having left them a long way off the pace in the Primera Liga title race.
In contrast, United head into midweek action 12 points clear at the top of the Premier League table and unbeaten in all competitions since 5th December - a 14-match run.
They have yet to hit their stride in Europe this season, having suffered two defeats at the end of the group stage, but are among the best in the business when it comes to raising their game for the big occasion.
Occasions do not come much bigger than a two-legged knockout tie with Real Madrid - with a managerial duel between Mourinho and Sir Alex Fergsuon, and Cristiano Ronaldo's first outing against United since leaving England for Santiago Bernabeu in 2009 providing intriguing subplots.