Heading down the season’s home stretch, primetime’s most popular series are flexing their muscles.

Action heated up on Fox’s “American Idol,” which whittled the field to its final three contestants. The show rose week to week — and also year to year — in helping the net capture its 14th consecutive victory among young adults.

And ABC’s “Grey’s Anatomy” has begun to reassert itself as primetime’s top scripted draw among young adults. Thursday’s episode, the final seg before this week’s two-hour season-ender, racked up the best demo score for any scripted series during the May sweep.

Last week, the medical drama also earned a rare victory over CBS timeslot rival “CSI” to stand as Thursday’s most-watched program.

Overall for the May 4-10 sesh, Fox stayed on top in adults 18-49 with a 3.2 rating/10 share, followed by CBS (2.7/8) and ABC (2.6/8) in a tight battle for second. NBC was further back in fourth (2.0/6), but up a tick year to year, followed by Univision and basketball-boosted TNT (both at 1.5/4).

Fox also edged out CBS to win in adults 25-54 (3.8/10 to 3.6/10) and won with a little more cushion among those 12-34 (2.3/8 to 1.9/7 for runner-up ABC). CBS made it 10 straight weeks as the most-watched network overall, averaging 10.8 million viewers to 8.9 million for second-place Fox.

“American Idol” was the week’s No. 1 program, with the Tuesday performance show (8.3/23 in 18-49, 23.41 million viewers overall) tying in demo rating with Wednesday’s results show (8.3/20, 23.57m). Combined, the two segs were up vs. the previous week and also up a bit vs. the corresponding week a year ago.

The net ruled the opening hour of Monday with “House” (4.6/13, 12.05m), while Wednesday rookie “Lie to Me” had its best showing in five weeks (2.7/8 in 18-49, 8.68m). Not so hot were Friday’s firstrun dramas “Prison Break” (0.9/3 in 18-49, 2.99m) and “Dollhouse” (1.0/4, 2.70m for its season finale).

For ABC, “Grey’s Anatomy” averaged a 5.4 rating/14 share in adults 18-49 and 15.55 million viewers overall — the show’s best numbers in seven weeks. The net also won the hour after “Grey’s Anatomy ” with the Michael J. Fox spec “Adventures of an Incurable Optimist” (3.1/9, 10.23m).

Elsewhere, the Alphabet had a strong Monday with “Dancing With the Stars” (4.8/13 in 18-49, 20.28m) and the best numbers in a while for rookie drama “Castle” (2.8/7, 9.97m). Net’s other new dramas, “Cupid” (1.6/4, 5.14m) and “The Unusuals” (1.6/4, 4.63m), remain limp, though.

Sunday sudsers “Desperate Housewives” (4.1/11, 12.29m) and “Brothers and Sisters” (3.0/8, 8.75m) hit lows on Mother’s Day, a night with lower viewing levels than usual.

CBS was paced by Monday comedy “Two and a Half Men” (5.0/12 in 18-49, 14.17m), one of nine programs on the network to rank among the week’s top 20 in 18-49.

That list also included each of the net’s other Monday skeins as well as Thursday reality vet “Survivor” (3.8/12, 11.99m) and Tuesday’s drama combo of “The Mentalist” (3.6/9, 16.68m) and “NCIS” (3.4/10, 16.72m). In total viewers, “NCIS” was the week’s No. 1 program — the 30th time in 33 frames this season that the Eye claimed the week’s top show.

NBC’s week started very quietly with the return of “Deal or No Deal” on Monday (1.2/3 in 18-49, 4.36m) but closed on a strong note Sunday with “The Celebrity Apprentice” finale (3.1/9, 8.81m), which built throughout its three-hour telecast and ended up winning the week’s final hour.

Also, “The Biggest Loser” had another strong showing on Tuesday (3.6/10 in 18-49, 9.13m) and remains the most-watched edition of the show since its 2004-05 season.

The net’s most recent additions, Thursday’s “Parks and Recreation” (2.1/6 in 18-49, 4.72m) and “Southland” (2.0/6, 6.61m), were both in line with their previous week’s OK results. “Parks” has consistently built on its “My Name Is Earl” lead-in.

CW was led by “America’s Next Top Model” (1.7/5 in 18-49, 3.82m) and “Smallville” (1.5/5, 3.39m), while Tuesday’s “90210” continues to put up tame scores (0.9/2, 1.84m).

Nickelodeon’s hourlong “iCarly” movie “iDate a Bad Boy” was the week’s most-watched cable program, pulling in 6.47 million viewers for its Saturday premiere. Roughly half the audience (3.3 million) was kids 2-11, while 2.8 million fell into the tween 9-14 category.

The NBA Playoffs dominated elsewhere in cable, with TNT surging to first place in key demos as well as total viewers. Among adults 18-49, the top eight cable telecasts of the week were NBA contests, led by Wednesday’s game between the Los Angeles Lakers and Houston Rockets (3.0/11 in 18-49, 6.32m).

In men 18-49 (4.4/16), the NBA game ranked fourth for the week — behind only the two editions of “American Idol” and CBS laffer “Two and a Half Men.”