Eyes across Europe and the world will be drawn to the Theatre of Dreams on Tuesday when the two biggest clubs on the planet battle it out for a place in the quarterfinals of the Champions League. After a 1-1 draw in the first leg at the Bernabeu, the tie couldn’t be more perfectly poised.

In theory, United are the favorites, having got the away goal, but Madrid and their counterattacking threat could be even more dangerous away from home.

Yet there is so much intrigue surrounding what should be a thrilling 90 minutes—and potentially more—on the pitch.

One man that demands attention wherever he goes will be in even greater focus than usual in the buildup to the match. Portuguese superstar Cristiano Ronaldo will return to grace the Old Trafford turf for the first time since his record £80 million transfer back in 2009.

Ronaldo was and remains adored by Manchester United fans. During his six years with the club he grew from a raw and flash teenager into the most devastatingly physically efficient player in the world. In doing so, the former Sporting Lisbon man helped United to regain their dominance in the Premier League and memorably claim a third European Cup.

While Ronaldo was desperate to move to the club he supported as a boy a year after scoring in the final of the Champions League, the mutual affection between him and United remains strong. The embrace between Ronaldo and Sir Alex Ferguson after the first-leg in Madrid was consistent with a relationship that the 28-year-old has likened to that between a father and a son.

There is sure to be plenty of embraces again between Ronaldo and United’s staff and players both before and after the match on Tuesday, but during the contest it will be all business, on both sides.

Ronaldo is not only the most intriguing storyline of the match off the pitch, but is likely to be on it too. It is Ronaldo that embodies Real Madrid’s chief threat—their ability to launch devastating, lighting-quick breaks.

And it is hard to imagine Ronaldo coming into the second leg in better form. In the past week alone, he has been the integral player in Madrid’s two defeats of their great rivals Barcelona. If United needed any further warning that he cannot afford to be left one-on-one with a defender then they surely will have received it. With Angel di Maria also returning to form and provided a double threat on the opposite flank, United will be risking a lot should they decide to play with their familiar attacking impetus at Old Trafford.

On the opposite side, it is a formerly flying winger and now calming midfield influence who will also be foremost in the minds of many as kick-off approaches. Perhaps only the presence of Ronaldo could relegate the occasion of Ryan Giggs’s 1,000th senior appearance to a secondary news line.

The Welshman recently signed another one-year contract extension that will incredibly see him turning out for United past the age of 40. While many were writing him off earlier in the campaign, Giggs is enjoying his best form of the season at just the right time.

Giggs has scored three goals in his last four starts and, having been rested in the victory over Norwich at the weekend, Ferguson has confirmed that he will play some part against Madrid.

With Phil Jones ruled out through injury, there is a very real possibility that the veteran could even start in the heart of the midfield. Jones did an exceptional shielding job in front of the back four at the Bernabeu to help limit Madrid’s counter-attacking potential, but Giggs would provide very different qualities.

Giggs can no longer get around the pitch to anything like the degree he once did and his selection alongside the similarly immobile playmaking skills of Michael Carrick would be a huge risk.

Whatever selection Ferguson makes, it is sure to be with his former charge Ronaldo firmly in mind.