“American Gladiators” was a strike hit, performing very well for NBC during winter months when repeats and untested unscripted fare ruled the networks. But facing strong competition on ABC, Fox and CBS last night, the second edition of “Gladiators” saw its ratings plunge.

The show’s two-hour return averaged a 1.9 adults 18-49 rating last night, according to Nielsen overnights, less than half the show’s 4.3 average during its winter run.

No doubt the show was hurt by the solid lineups on the other networks, which all turned in good performances from 8 to 10 p.m., averaging a 4.0 or above.

“Gladiators” actually finished behind Univision during the two-hour slot as well. Perhaps the good news for NBC is that the strong-man series will only face this hefty competition for one more night, with May sweeps ending next week. After that the networks will roll out their less-daunting summer schedules.

Still, the ratings are a disappointment for the network. “Gladiators” is one of the tentpoles of NBC’s summer schedule, which will include some 300 hours of original programming as the network pushes to establish a year-round schedule.

Meanwhile, Fox was first for the night among viewers 18-49 with a 4.5 average overnight rating and a 12 share. CBS was second at 4.0/10, ABC third at 3.7/10, NBC fourth at 2.2/6, Univision fifth at 1.8/5 and CW sixth at 1.2/3.
 
ABC began the night in the lead with a 3.9 rating at 8 p.m. for the first hour of “Dancing with the Stars,” with CBS second with a 3.4 average for “The Big Bang Theory” (2.9) and “How I Met Your Mother” (3.8 for Britney Spears’ second guest appearance, down from a 4.5 for her first appearance in March). Fox was third with a 3.2 for “Bones,” Univision fourth with a 2.1 for “Al Diablo con los Guapos,” NBC fifth with a 1.8 for “Gladiators” and CW sixth with a 1.2 for “Gossip Girl.”
 
At 9 p.m. Fox took the lead with a 5.8 for “House,” while CBS remained second with a 4.6 average for “Two and a Half Men” (5.0) and “Rules of Engagement” (4.1). ABC was third with a 4.0 for the end of “Stars” (4.7) and an episode of “Samantha Who?” (3.2), Univision fourth with a 2.1 for “Fuego en la Sangre,” NBC fifth with a 1.9 for another hour of “Gladiators” and CW sixth with a 1.2 for “One Tree Hill.”
 
CBS took over at 10 p.m. with a 4.0 for “CSI: Miami,” followed by ABC with a 3.3 for the season finale of “The Bachelor.” NBC was third with a 2.9 for the season finale of “Medium” and Univision fourth with a 1.3 for “Cristina.”
 
Among households, ABC led the night with a 9.3 average overnight rating and a 15 share. Fox was second at 7.5/11, CBS third at 7.3/11, NBC fourth at 3.7/6, Univision fifth at 2.1/3 and CW sixth at 1.8/3.