Inter held at home by lowly Torino
Rolando Bianchi gave Torino the lead with a header just after the break before defender Nicolas Burdisso nodded the equaliser for the champions, who piled on the pressure in the closing stages and hit the post twice.
Inter's lead remains six points after Milan moved above Juventus with a 3-0 win at Lazio in the late game.
In-form Beckham, on loan from Los Angeles Galaxy, crossed for Alexandre Pato to score on 42 minutes and then whipped in a free kick which Massimo Ambrosini headed home early in the second half.
Kaka netted late on but Lazio had their opportunities with Milan goalkeeper Christian Abbiati producing some fine saves.
Juve lost 3-2 at home to Cagliari on Saturday and now lie seven points behind Inter.
Since the mid-season break, Inter have drawn with Cagliari, been easily beaten at Atalanta, scraped a win at home to Sampdoria and played well in Wednesday's 2-0 victory at Catania.
The Torino game followed the inconsistent pattern with Inter only coming to life late on after a forgettable first half.
Hernan Crespo and Zlatan Ibrahimovic hit the woodwork in a frantic finish and Inter substitute Ricardo Quaresma, heckled by his own fans, spurned a great chance. Torino's Ignazio Abate was also lucky not to concede a penalty for handball.
"I never like drawing at home but I accept it. We created lots of chances but Torino defended with a fantastic spirit," Inter coach Jose Mourinho told Sky as he bemoaned Sulley Muntari's suspension and Dejan Stankovic's first-half injury.
Genoa remain fourth thanks to Domenico Criscito's 88th minute goal in a 1-0 home win over Palermo.
AS Roma, who had won their last four league games, are fifth after drawing 2-2 at bottom side Reggina on a very muddy pitch.
Striker Bernardo Corradi put the hosts ahead with a penalty but a David Pizarro brace gave Roma the lead before Francesco Cozza capitalised on Simone Loria's mistake.
Bologna vs Fiorentina was postponed until Monday after snow.
All Italian games this weekend kicked off 15 minutes late because of a protest over the Court of Arbitration for Sport banning Napoli's Daniele Mannini and Brescia's Davide Possanzini for a year for being late for a 2007 drugs test.