David Beckham is not guaranteed to start for Milan in Tuesday's last-16 first-leg match against his former side United.
The midfielder has been on the bench for the last two league games and the return from injury of forward Alexandre Pato makes it even less likely the 34-year-old will play.
However, coach Leonardo knows how much it means for Beckham to face Alex Ferguson's men for the first time even if the former England captain is trying to stay cool.
Milan have never lost to United over two legs and have won their four encounters in Italy. On-loan Beckham came on with 15 minutes left against Udinese and played one dreadful pass which almost led to an opposition goal.
Worse for Milan was a thigh muscle injury which forced centre back Thiago Silva to go off.
The Brazilian is battling to shake off the problem for Tuesday and partner fit-again Alessandro Nesta at the back while striker Marco Borriello is a doubt and Klaas Jan Huntelaar could again deputise, having scored twice against Udinese.
Ronaldinho had one of his better games on the left of the front three but the return of Brazilian compatriot Pato, out since the start of the year with a thigh problem, will give Milan more pace on the right.
English champions United have fewer injury worries but centre back Nemanja Vidic has stayed at home because of a nerve problem in his leg and Beckham's former team-mate Ryan Giggs is out with a broken arm.
United striker Wayne Rooney is in the form of his life but is taking nothing for granted against the seven-times champions.
Lyon will not be obsessing about Cristiano Ronaldo in their home fixture against Madrid as the La Liga side have plenty of other weapons in their arsenal, according to coach Claude Puel.
The Portuguese forward looked in ominous form on Saturday on his return from a two-match La Liga suspension, netting twice, but Puel told Spain's Marca sports daily they would not be marking him man-to-man at the Stade de Gerland.
"There is so much potential that I don't believe that one player will make the difference," Puel said, listing Brazilian playmaker Kaka, former Lyon striker Karim Benzema and forward Gonzalo Higuain as significant potential threats.
Lyon defeated Real on the last two occasions the clubs met in France, although Manuel Pellegrini's side are unbeaten away in this season's Champions League.
They are seeking a first quarterfinal place since 2003/04 and this year's competition has a special edge for the nine-times European champions as May's final is at their Bernabeu stadium.
Lyon have struggled this season, going out of both the French Cup and the League Cup, and ended 2009 in sixth place in Ligue 1.
The move to play the round of 16 will be played on eight different evenings spread over a month featuring two games a night, rather than four evenings with four matches a night was designed to allow more fans to see the matches on television.
The two other ties kicking off this week -- February 17 -- are between Porto and Arsenal and Bayern Munich and Fiorentina, with the return legs on March 9.