The Serie A clash ended 2-2 with the 33-year-old having one decent shot, delivering several crosses and carrying out his defensive duties as part of a midfield three.
Beckham, who is on loan from Los Angeles Galaxy for two months, was playing his first competitive game since October.
"I thought it was great, I enjoyed it immensely, I was surprised to start the game," he told reporters.
"Of course I'm still working on my fitness but I felt good, better than I thought I would in the game. (My aim) is to play as many games as possible and work on my fitness and just be part of AC Milan. I feel very lucky."
Beckham, who stood by as team mate Ronaldinho took an early freekick at goal, did not look out of place in Serie A.
"It's similar (to other leagues), of course there's more of a tactical level in Italy but I think I adapted pretty well," he said.
"We take it in turns, if another player feels like scoring from a freekick I let them do that. I'm sure Ill get a chance at some point. They speak pretty good English, the majority of the players, and football is an easy language to learn."
CHASING MOORE
Beckham wanted competitive football during the U.S. close season to stay in the England reckoning for February's friendly with Spain.
The former captain, who has 107 caps and needs two more to beat Bobby Moore's outfield record, reiterated that he will return to Los Angeles in early March.
"That's what's been agreed and that's what I'll stick to," he said.
On Saturday, Milan coach Carlo Ancelotti said that Beckham would almost certainly be on the bench, but instead opted to start him.
"Beckham has shown in the days he has been with us that he is a tactically-clever player, serious and well-balanced. Starting him was a little reward for inserting himself well into our group," Ancelotti told Sky after the game.
