Injuries to Alexandre Pato and Clarence Seedorf meant second-placed Milan had to start on-loan Beckham further forward than usual on the right of a front three.
"He had a week where we tried him in every role (in training)," coach Leonardo told Sky television.
"I think that is the synthesis of what he is all about. He has an absolute willingness to help, extraordinary quality and tactical intelligence."
The Los Angeles Galaxy midfielder is on-loan at Milan for a second five-month loan spell in a bid to clinch a place in England's World Cup place during the U.S. close season.
He produced some superb crosses, went close with a drive and worked hard defensively in front of England coach Fabio Capello.
The 34-year-old even turned down Ronaldinho's offer to take a penalty at 4-1 and the ball was given to Klaas-Jan Huntelaar, short of goals since his move from Real Madrid in August.
"Beckham, just like last season, has been a great acquisition. He is a superb player and a superb person," Milan chief executive Adriano Galliani said.
"He earns very little from us. He came to Milan for all different reasons than money."
