Rock said Law was "second choice" for casting agents after Tom Cruise.
"You want Tom Cruise and all you get is Jude Law? Wait. It's not the same thing. Who is Jude Law? Why's he in every movie I have seen for the last four years. He's in everything.
"Even the movies he's not in, if you look at the credits he made cupcakes or something. He's gay, he's straight, he's American, he's British, next year he's playing Kareem Abdul Jabbar."
Three hours later, when Penn arrived on stage to present the Best Actress award he defended Law, his co-star in All the King's Men which is filming in New Orleans.
The fiery actor began his rebuke by asking the Academy to "forgive my compromised sense of humour".
He went on: "I just want to answer our host's question about who Jude Law is - he's one of our finest actors."
Announcing Hilary Swank's award he said: "What Jude and all talented actors know is that for every great, talented actor, there are five actresses who are nothing short of magic."
Frågan#1
Vad - exakt - sa Sean Penn om skämtet Chris Rock drog om Jude Law... och hur löd det skämtet förresten? Finns videosekvenser nånstans? Eller transcripts? :q