NBC made it look easy last week, winning by ridiculous margins once again thanks to the London Olympics.

The Closing Ceremony on Sunday drew about 31 million viewers to cap the most-watched Summer Games held outside the U.S. since 1976. Still, the net couldn’t immediately parlay its plentiful promotion during the Games into immediate ratings gains as reality show “Stars Earn Stripes” opened modestly to kick off this week (see below).

While NBC’s rivals were mostly in reruns during the Games, Univision stepped up in a big way. The Spanish-language broadcaster was the week’s top-rated primetime alternative to NBC among young adults, boosted by the finale of novela “La Que No Podia Amar.”

Overall, according to Nielsen estimates for Aug. 6-12, NBC averaged a 7.9 rating/23 share in adults 18-49, followed by Univision (1.1/4), CBS (1.0/3) and ABC and Fox (both 0.9/3). The Peacock was so primo that it beat the next 11 top-rated networks combined in the demo.

And it was nearly the same in total viewers, where the net’s average primetime aud of 26.1 million topped the combined deliveries of the next 10 nets.

The seven nights of Olympics, plus Sunday special “London Gold,” easily accounted for the week’s eight top-rated programs in all categories. Best scores among young adults were competition nights of Tuesday (9.6/28) and Wednesday (9.4/27), and the largest overall aud came for the Closing Ceremony (31.01 million), up 12% from the final night in Beijing four years ago.

All 17 nights of these Olympics drew a larger audience than the comparable night in 2008, and 14 of the 17 matched or fared better than Beijing in adults 18-49.

Meanwhile, Univision kept the lights on with an all-original lineup including “La Que No Podia Amar” (The One That Couldn’t Love). It wrapped with a two-hour finale Friday that averaged a 2.3/8 in 18-49 and 5.83 million viewers overall, peaking with nearly 8 million.

And underscoring the fact that a good chunk of the Univision aud didn’t watch the Olympics, “Podia Amar” exceeded its prior average since bowing in January by more than 500,000 during its Olympics run.

And overall for the full two weeks of the Olympics, Univision grew over its prior summer average by 7% in 18-49 while CBS (-2%), CW (-11%), Fox (-20%) and ABC (-43%) all tumbled.

CBS’ “Big Brother” was the top broadcast series in 18-49 last week (led by Sunday’s 2.0/5); Fox’s reality series aired repeats.

In cable, HBO’s “True Blood” was again the top series of the week in 18-49 (2.6/7, 4.49m).

A couple of rookie dramas wrapped last week with upticks: TNT’s “Dallas” (1.3/3, 4.29m), Wednesday’s top cable show in 25-54 (1.6/4), and A&E’s “Longmire” (0.9/2, 4.34m), which drew its biggest crowd yet.

On Monday of this week, NBC’s patriotic-themed reality contest “Stars Earn Stripes” from Mark Burnett and Dick Wolf opened unimpressively (1.7/5 in 18-49, 5.24m) from 8 to 10 p.m., edging up in its second hour. That earned it a second-place finish, but the net had to be hoping for better the night after the Olympics wrapped.

Looking a bit healthier was the second-season premiere of “Grimm,” which led among the broadcasters in the 10 o’clock hour (2.0/5 in 18-49, 5.7 million viewers overall), its second best score to date.

At Fox, Gordon Ramsay’s latest, “Hotel Hell,” opened OK (1.9/6 in 18-49, 5.12m) — winning the 8 o’clock hour in 18-49 in the highest-rated series premiere of summer in the demo (admittedly not that high a bar).