There’s a new leader on Monday night. NBC, boosted by hit returning game show “Deal or No Deal” and a decent debut for much-buzzed-about new drama “Studio 60 on the Sunset Strip,” edged CBS for No. 1 on a competitive evening.

NBC averaged a 4.9 adults 18-49 rating and 13 share for the night, just ahead of CBS’s 4.7/12, according to Nielsen overnights. “Deal” helped NBC win the night’s first two hours with CBS claiming No. 1 at 10 p.m.

CBS’s average was down 4 percent from the same night last year, when it averaged a 4.9 on the opening night of the season. NBC was up 17 percent over last year’s 4.2.

“Deal” was an easy No. 1 from 8 to 10 p.m., averaging a 4.3 at 8 p.m. and a 5.5 at 9 p.m., peaking with a 6.0 in its final half hour. It also dominated total viewers, averaging 14.3 million its first hour and nearly 17 million its second, bettering the No. 2 shows by more than 3 million.

The results were more mixed for “Studio 60.” While the new Aaron Sorkin show, tabbed by many critics as the best of the new season, averaged a 5.4 in its first half hour, just 0.3 behind CBS’s “CSI: Miami,” it dipped an alarming 15 percent in its second half to a 4.6. It averaged a decent 5.0 overall.

Still, it was up about 10 percent over the premiere of “Las Vegas” in the same timeslot last year. And what NBC really wants from the show is strong ratings from the affluent, educated and advertiser-coveted viewers who stayed loyal to Sorkin’s “West Wing” for years. Among 25-54s, the show averaged a 6.0, 1.2 behind “Miami.”

Meanwhile, Fox and ABC tied for third on the night with a 3.3/8 apiece, followed by a 1.9/4 for Univision and a 0.8/2 for the CW.

Though the latter, emerging from the combination of UPN and the WB, did start programming last night, its official debut is not until tomorrow night, when “America’s Next Top Model” launches. Ratings for Sunday through Tuesday will not be included in any official estimates for the CW.

“Deal” finished first at 8 p.m. last night with a 4.3, followed by Fox’s “Prison Break.” The series premiere of CBS’s “The Class” averaged a 3.7, or 0.3 better than former timeslot occupant “King of Queens” last year. Lead-out “How I Met Your Mother” averaged a 3.8. ABC’s “Wife Swap” averaged a 2.9, Univision’s “La Bella Mas Fea” averaged a 2.1, and a repeat of “Seventh Heaven” on the CW did a 1.0.

At 9 p.m., “Deal” jumped to a 5.5, with CBS’s “Two and a Half Men” (5.0) and “The New Adventures of Old Christine” (4.2) second at 4.6. ABC’s “Wife Swap” averaged a 3.9, followed by Fox’s “Vanished” at 2.7, Univision’s “Barrera de Amor” at 2.1, and CW’s “Launch of a Network” at 0.6.

At 10 p.m., CBS grabbed the lead with “Miami’s” 5.7, down 12 percent from last year’s 6.5 for its premiere. “Studio” was second at 5.0, ABC’s “Supernanny” third at 3.1, and Univision fourth at 1.7.

Among households NBC also won with a 9.3/14, followed by CBS at 9.0/14, Fox at 5.3/8, ABC at 5.1/8, Univision at 2.3/4 and the CW at 1.4/2.