The premiere of "The Late Show With Stephen Colbert" on CBS averaged 6.6 million viewers. That won the time slot, ahead of The Tonight Show's 2.9 million viewers on NBC and Jimmy Kimmel Live's 1.75 million on ABC.

Colbert's 6.6 million total also beat most of the prime time shows on other networks.

24 hours later, Stephen Colbert’s second broadcast as host of CBS’s “The Late Show” drew 3.7 million viewers, a 44% drop from the 6.6 million that watched his debut show on Tuesday. NBC’s “Tonight Show with Jimmy Fallon” had 4.1 million viewers, an increase of 39% from the previous evening’s audience. This is according to Nielsen ratings.

Time will tell if David Letterman's replacement will hold his own against Jimmy Fallon and Jimmy Kimmel.