WE love these games above all for the birds of prey: the swooping predators who provide the kill.
For Wayne Rooney here, the challenge was no less than to prove himself worthy of comparison with Cristiano Ronaldo in a fixture that has sparkled with the talents of George Best, Bobby Charlton, Zinedine Zidane and Brazil's Ronaldo.
There is no higher measure of judgment for a game-changing talent than a Real Madrid-Manchester United tie. Butterflies seldom trouble the stomach this much as early as the round of 16. The real tension comes later.
Yet as soon as the weekend's domestic business was out of the way you could feel the rumble in the ground from Robin Van Persie v Karim Benzema, Rooney v Ronaldo, a contest that was won emphatically by the star of Castille.
First blood in the battle of the big names went to Ronaldo, a master of land and air, who has perfected the art of hang-time when balls are swung into the box.
Where did he learn to head so well? At United, where he scored 42 times in their Champions League winning campaign of 2007-08. Now in his net-busting prime at 28, Ronaldo rose, suspended himself above Patrice Evra and met a perfect Angel di Maria cross with his forehead to cancel out a similar goal from Danny Welbeck.
Yes, the youngsters had a say as well. Welbeck's 20th-minute opener for United was his first away from home in the Champions League and only his second in 28 matches. He may not have the numbers yet of a great striker but he has the big-match instincts, as he showed with England at Euro 2012.
Rooney could at least claim a part in the goal. It was his corner-kick that eluded Sergio Ramos and allowed Welbeck to announce himself to the Bernabeu. Overall, though, Ronaldo won the first-half bragging rights.
R & R were a potent combination in the United side of five years ago but Ronaldo left Rooney behind to become Lionel Messi's rival in the Iberian struggle to be known as football's No 1 luminary.
Those hoping to see sentiment intervene on United's behalf were bound to be disappointed. Ronaldo was not going to let old affections soften his appetite for destruction, though his goal celebration was more muted than such a charged occasion would usually deserve.
Every year since his more famous accomplice left Old Trafford, Rooney has suffered by comparison. An extremely good player, he has toiled to be known as a great one. Stepping out of Ronaldo's shadow was not the liberation he probably expected. Real Madrid's poster boy went stratospheric while Rooney remained mostly earthbound.
But this was a chance to redress that balance, to barge his way into the platinum club dominated by Messi and Ronaldo. Even now he is not the top goal-scoring talent in United's starting XI. That title belongs to Van Persie, who has scored 12 times in his last 14 outings for Alex Ferguson's side.
Rooney, a year younger than his old accomplice, had plenty of motivation. Described by a local columnist as a "hooligan" who had almost wandered down from a beer-swilling crowd, England's leading striker is not fond of being talked down to. The same writer called him "El Coco", which means the "bogey man," a description better suited these days to Van Persie.
Rooney started on the right side of United's midfield, on Ronaldo's flank, with Welbeck on the opposite touchline and Shinji Kagawa through the middle behind Van Persie. The game was soon a compelling dance of attack and counter-attack, with balls whipped into the box with lethal precision and quick forays across the ground.
Ronaldo shone in his white No 7 shirt. He tormented Rafael at right-back and made a statue of Evra for Real's equaliser. Part of Ronaldo's appeal is the range of his talents: speed, power, left foot, right foot, headers, and enough deftness in his passing around the box to make him a master of the assist.
Rooney, on the other hand, had a more confined role which required him to help Rafael defensively while also trying to pin back Fabio Coentrao. There is no escaping the fact that his core fitness comes into question in games like these.
Ronaldo is Olympian. Rooney's radiator tends to steam and hiss a bit after half an hour of strenuous exertion and he relies on willpower to carry him through the onset of fatigue.
With six minutes left, Rooney had no more to give and the fresher legs of Anderson were sent on to help preserve United's share of the game.
The next thing we saw was Ronaldo lower his head and strike a free-kick with that physics-defying up-down trajectory. The ball dropped on the roof of the net and sent the string into waves. Appreciative and frustrated groans filled the Bernabeu.
Ronaldo was the gleaming aristocrat of this game and Rooney laboured in his shadow. But United went home the more satisfied. (© Daily Telegraph, London)