Fox’s first-year Tuesday medical mystery continues to perform like a “House” on fire, this week holding off tougher competish than usual in the night’s middle hour and retaining the largest portion yet of its hefty “American Idol” lead-in.

On the first Tuesday of the May sweep, Fox’s hot “Idol” and “House” dominated from 8 to 10, while NBC closed the evening out with a strong showing for the concluding hour of an expanded “Law & Order: Special Victims Unit” featuring guest stars Angela Lansbury and Alfred Molina.

According to Nielsen, “American Idol” showed no ill effects from the controversy surrounding judge Paula Abdul, crushing the competish with a 9.9 rating/28 share in adults 18-49 and 24.42 million viewers overall. Talent show was up 10% year-to-year and matched the combined 18-49 deliveries of the other five broadcast nets.

“House” followed at 9 with winning scores across the board (7.0/17 in 18-49, 17.14m), retaining a best-yet 71% of its 18-49 “Idol” lead-in. Perf was especially impressive since it faced atypical Big Four drama competish from the special “Law & Order: SVU.”

“House” shot up 46% from the 18-49 score for “24” in the hour a year ago (4.8/12), helping Fox notch nice year-to-year improvements as it dominated the night in all key categories.

For NBC, the two-hour crossover event between “Law & Order: SVU” and Friday entry “L&O: Trial by Jury” averaged a sturdy 5.3/13 in 18-49 and 16.54 million viewers overall — the net’s best showing in the 9-11 p.m. block since Jan. 11. First hour scored a 4.3/11 in the demo, with the conclusion (which included the cast of “Trial by Jury”) notching a 6.3/16.

CBS ran second all three hours in 18-49 with “NCIS” (3.1/9 in 18-49, 13.55m), “Amazing Race 7” (5.2/13, 12.84m) and the season finale of “Judging Amy” (3.0/8, 10.80m). “NCIS” shot up a steep 50% in 18-49 from the same frame a year ago (2.1/6).

Also, ABC’s Tuesday struggles continued as 10 o’clock drama “Blind Justice” logged its lowest scores to date (2.3/6 in 18-49, 6.00m), but it was another good night for the WB’s combo of “Gilmore Girls” and “One Tree Hill” — both up more than 10% year-to-year in key demos to help the Frog place No. 2 to Fox in femmes 12-34 (3.8/10).