By Lynette Rice
Updated October 15, 2010 at 09:15 PM EDT

All eyes have been on the winners and losers in prime time since the 2010-11 season started last month, but the competition in late night has stayed no less fascinating. To wit: For the week ending Oct. 8, David Letterman matched Jay Leno among adults 18-49 for the first time this TV season and won the week in adults 25-54, according to Nielsen ratings.

The Late Show and The Tonight Show both posted a 0.9 rating/4 share in the key demographic. Leno still led Letterman in total viewers (3.5 million versus 3.4 million) but its always worth noting when the CBS host manages to catch up (or even beat) the chinned one in the demo NBC traditionally dominates in the 11:30 hour. Each 18-49 ratings point represents 1.3 million viewers.

But the season is still young. In fact, Tonight has led Late Show by a 5 percent margin in 18-49 viewers (1.2 million vs. 1.2 million) for the first three weeks of the season, NBC reports, which reverses the order at this same point a year ago, when Late Show held a 12 percent lead (1.5 million vs. 1.3 million). In total viewers, Tonight also leads Late Show through three weeks of the new season by a 3 percent margin (3.7 million vs. 3.6 million).

Season to date, Leno is leading in 18-49 in late night with a 1.0/4, followed by Nightline (1.0/4), Letterman (0.9/4), Jimmy Fallon (0.6/3), Jimmy Kimmel (0.5/3), Craig Ferguson (0.5/3) and Carson Daly (0.4/3). In total viewers, Leno also leads with 3.7 million, followed by Nightline (3.7 million), Letterman (3.6 million), Kimmel (1.7 million), Late Night (1.7 million), Late Late Show (1.8 million) and Daly (1 million).