ABC has wrapped up a Dec. 20-26 primetime Nielsens triumph with its best Christmas-week rating in four years.It’s ABC’s third weeklong win in a row, putting the Alphabet net even with CBS with seven victories apiece after 14 weeks of the season. ABC is ending the fourth quarter with its highest rating since 1989 and best competitive position since 1979. Keys to ABC’s triumph last week were the always powerful “Home Improvement” and “Roseanne,” another strong “Monday Night Football” telecast and the usual Friday sweep despite low Christmas Eve viewership. The holiday week always brings depressed viewership and often all-time worst regular-season ratings, but this year’s numbers were generally respectable. Only NBC flirted with record lows, slumping to the second-lowest regular-season weeklong rating, ahead of only its own ’92 Christmas-week score. The week’s adults 18-49 averages were ABC, a 6.6 rating/19 share; NBC, 5.8/17 ; CBS, 5.6/16; Fox Broadcasting Co., 4.5/13. ABC won every night by that measure except Thursday and Saturday, both of which went to NBC. Monday On Monday of this week, ABC’s Miami-San Diego gridcast (15.7/27) won the night with a little help from “Day One” (10.6/18). The ABC newsmagazine equaled its highest rating and best competitive slot position since Aug. 30, landing a mere 2 shares out of the slot lead. A special “Bob” (11.9/19) retained 86% of its “Murphy Brown” lead-in (13.9/22 ), the weakest perf in that Monday 9:30-10 p.m. slot for CBS since Nov. 8. “Murphy Brown” itself is getting blitzed by football, having won the 9-9:30 half-hour just once in its last 10 airings. Sunday CBS swept all the Sunday half-hours for the sixth time in seven weeks, led by the top-rated show of the week, “60 Minutes.” But as is often the case, CBS dropped Sunday among adults 18-49, losing this time to ABC. NBC’s “seaQuest DSV” continued to founder, plunging again to series-low depths. Fox’s “Living Single” and “Married … With Children” both won their half-hours in the adults 18-49 demographic. Saturday Christmas-night football and basketball rallied NBC to its first Saturday win since Oct. 9. Among adults 18-49, NBC enjoyed its most lopsided Saturday victory since Aug. 8, 1992, during the Barcelona Olympics. At a time when pro football is sometimes criticized as a declining sport lacking in drama, while pro basketball is praised as a hot, growing sport, it’s worth noting that Saturday’s Houston Oilers-San Francisco 49ers pro football post-game show earned a 12.5/28, 39% higher than the pro-basketball Orlando Magic-Chicago Bulls game that followed (NBC’s highest-rated Christmas hoopcast yet). Friday On Christmas Eve, ABC unwrapped its fourth straight sweep of the Friday half-hours despite CBS Yule spex that delivered the Eye web’s second-best Friday 8-10 p.m. share since Oct. 8. Low Christmas Eve viewership levels knocked NBC down to its worst-rated Friday since last Jan. 1. That was the night a Florida State-Nebraska Orange Bowl (which served as a precursor to this Saturday’s Orange Bowl, which will determine the national championship) earned a mere 4.2/7 from 8-11 p.m. Last Friday’s “X-Files” uncovered the series’ best share in three months. Thursday NBC’s all-sitcom lineup won the night by a share in households and by 9 shares among adults 18-49. The struggling “John Larroquette” and “Cafe Americain” got important sampling, but neither excelled in their special Thursday slots. Fox’s “Cool Like That” Yule spec held 81% of its “Simpsons” lead-in rating, a better retention than what the last seven airings of “Sinbad” have managed in that half-hour. ABC’s “World of Discovery” spec on wolves earned that net’s best Thursday 8-9 p.m. share in five weeks. Wednesday ABC reported another Wednesday win with the help of “Lois & Clark,” which in rerun topped the last four “Moon Over Miami” results in the Wednesday 10-11 p.m. hour. Also, “George” joined that night’s ABC schedule. The sitcom starring boxer George Foreman punched out a 9% improvement on its “Thea” lead-in. CBS’ 29th run of “A Charlie Brown Christmas” was the second-lowest rated so far. But it was also the Eye web’s cheeriest rating in that slot since the World Series, leading to the best regular-slot “Nanny” numbers since that sitcom premiered Nov. 3. CBS’ disastrous 9-10 p.m. results have taken a toll in the 10-11 p.m. hour, where, without a respectable lead-in, “48 Hours” is running down 18% from its year-ago average. Tuesday ABC’s lineup was strong enough to take the night despite an all-rerun slate. Monday Giants-Saints football won a third-straight Monday for ABC, due in part to season lows for all five CBS Monday regulars (Daily Variety, Dec. 22). In evening news, second-place NBC (10.3/20) reported its highest share since Feb. 25 to March 1, 1991, and finished the closest its been behind leader ABC ( 10.5/20) since Sept. 18-22, 1989. Each rating point represents an estimated 942,000 households, or 1% of the country’s TV homes. The share is the same sort of percentage, except that it’s measured against only the households in which TV is being watched during the timeslot involved.