The UEFA Champions League round of 16 first legs conclude with Atlético versus Manchester United and Benfica at home to Ajax.
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The last of the UEFA Champions League round of 16 first legs offer up another batch of potential headline-makers, intriguing sub-plots and players to keep a close eye on.
Presented by Expedia, we run the rule over the major stories in prospect.
Round of 16 first legs: week two
Ronaldo out to breach Atlético's fortress
Atlético's record in Madrid in the UEFA Champions League knockout stage is quite remarkable – 14 games since 1997, nine wins and no defeats. If anyone can scale the Estadio Metropolitano rampart, however, it is surely Cristiano Ronaldo, who has scored 25 career goals against Atleti, with his seven in the Champions League including an extra-time penalty in the 2014 final. He also delivered during the shoot-out of the 2016 showpiece.
Ronaldo's influence for United this season has arguably been matched only by David de Gea at the other end of the pitch. The Spain keeper has been in sensational form and is sure to want to pull out all the stops when he faces his former side for the first time since he left in 2011.
Can Haller keep his scoring run going?
Benfica vs Ajax is one of only two ties – along with Inter vs Liverpool – pitting together two former winners. Erik ten Hag's Ajax look to be a vintage model, racking up six group stage wins out of six thanks to a fluent, fluid, possession-based style of football.
The man crossing the Ts and dotting the Is at the top end of the pitch has been Sébastien Haller, the first player ever to score ten goals in his first six UEFA Champions League matches, and only the second – after Cristiano Ronaldo, no less – to find the net in all six group games. How much longer can he keep the sequence going?
Away goals rule abolished
The away goals rule has been scrapped for the 2021/22 campaign. This means that ties in which the two teams score the same number of goals over the two legs go straight to two 15-minute periods of extra time. If the teams score the same number of goals, or no goals, during extra time, a penalty shoot-out is required.