Sir Alex Ferguson's prime objective is to ensure that Rooney remains in his personal jet stream until a possible Champions League final in Madrid on May 22, yet Fabio Capello must wring another seven weeks of energy and inspiration from him if England are to emerge from Johannesburg's Soccer City on July 11 with the World Cup in their grasp.
For both club and country, it all revolves around Rooney. Lose him to injury or fatigue between now and July and hopes of success within Old Trafford and Wembley will plunge through the floorboards.
But while the curse of the metatarsal remains in the lap of the gods, Beckham has no fears over Rooney's ability to last the pace.
The former England captain experienced Rooney's rising confidence at first hand in the San Siro and he fully expects him to prove as destructive for England as he currently is for United.
Beckham said: "Burn out won't be a problem because Wayne is ready for any game.
"It doesn't matter how many games he has played or how many he will be involved in to the end of the season, he will be ready for anything. He can sustain that level until the middle of July, of course he can. He is only 24, so he should be able to!
"He looks after himself and he works hard. The way he plays on the field is the way he plays in training and that is why he is so good.
"Without a doubt, he is one of the best goalscorers in the world and I have always said that about him. If he continues to do that, United will be even more successful than they already are."
Rooney's recent development, particularly over the last two months, has prompted Ferguson to claim that he now belongs alongside the modern-day greats of Cristiano Ronaldo, Lionel Messi and Kaka.
The three men have each received the prestigious Ballon d'Or award as European Footballer of the Year during the past three years, plus the World Player of the Year title, and now 'Goldenballs' is tipping Rooney for the Golden Ball.
Beckham said: "I hope he is a contender for the World Player of the Year and Ballon d'Or. I would love to see him win every title possible. That is the way I look at Wayne.
"I have seen him from being a young lad. I played in his debut for England and I have watched him score goals week in and week out and scoring at the highest level, too. It is amazing to see.
"He is certainly looked upon as a great player in Italy. That is all the Italian people care about – whether he is doing the right thing and scoring goals. That is what they see. They see him scoring goals and working hard. The Italian people and Milan fans love people who work hard."
Rooney stole Beckham's thunder on a night when the former United midfielder faced his previous employers for the first time and Milan must prevent a repeat of that if they are to overturn their first-leg deficit at Old Trafford on March 10.
Barring an extended stay at Milan beyond the end of this season, the second-leg could be the first and last time that Beckham tackles United on their home turf.
But the 34 year-old remains hopeful that the Italians can overcome Rooney's side and progress to the quarter-finals.
Beckham said: "It doesn't matter whether there is half the game left or two minutes left, United players are brought up to believe they can win even with a minute left. But the tie isn't over.
"We know how difficult it is going to be because nobody goes to Old Trafford and gets given gifts. We are going to have to work hard and play well and if we do that we have a chance.
"Personally, I am motivated any time I come out of any tunnel but it will be a nice night at Old Trafford."