The on-loan LA Galaxy midfielder knows Milan are now just six points behind their rivals with a game in hand.
Beckham said: "The derby is a game where favourites don't exist. For me it won't be important to score, but it will be important to do well and catch Inter."
The former England captain also had praise for Ronaldinho who scored his first ever hat-trick on Sunday in Milan's stunning 4-0 victory over Siena.
"It doesn't surprise me," Beckham admitted. "He played a great game. He is used to doing incredible things."