The final appearance of Robert Downey Jr. on “Ally McBeal” boosted that series Monday to its best ratings since February, helping Fox win easily in key demos for a second straight night.

According to Nielsen, “Ally” topped CBS’ second-place comedies by a combined 2 shares in adults 18-49 (6.8/17 vs. 6.0/15) and gave the series rare year-to-year ratings growth. It teamed with a timeslot victory in adults 18-49 for “Boston Public” (4.9/14) to give Fox the night by 3 shares in the key demo and help pull the net into a second-place tie for the May sweep.

Through Monday (19 nights of the four-week sweep), NBC remains comfortably ahead in adults 18-49 with a 4.8 rating/14 share (down 9% in rating vs. a year ago), followed by CBS, 4.2/12 (up 24%), which is tied with Fox, 4.2/12 (up 5%); ABC, 3.9/11 (down 28%); and the WB, 1.6/5 (up 14%), tied with UPN, 1.6/5 (down 6%).

CBS, which took Monday in total viewers, remains well ahead of the May sweeps pack with an average of 13.20 million (up 13% vs. a year ago), followed by NBC, 11.48m (down 6%); ABC, 10.74m (down 29%); Fox, 8.62m (up 5%); UPN, 3.72m (down 10%); and the WB, 3.57m (up 7%).

The Eye’s “Everybody Loves Raymond” was the night’s most-watched program (17.22m), while the net’s “Family Law” rallied to its best ratings in eight weeks (10.82m, 3.8/10 in A18-49) but remained mired in third place.

NBC hopped over CBS to take second place in adults 18-49 (4.7/13 vs. 4.6/12). Quizzer “Weakest Link” finished a solid second (4.6/13), “Dateline” nabbed its best score in 11 weeks (4.5/11) and “Third Watch” (5.1/14) matched its best share since premiere week.

Elsewhere Monday, ABC grabbed its second best movie numbers in 12 weeks with a repeat of “Con Air” (10.36m, 4.5/12). Pic put ABC in first on the night in all adult male demos and captured its final hour by nearly every measure.

The WB’s “7th Heaven” (7.27m, 3.0/9 in A18-49) drew big numbers with the first of a two-part season finale, taking its hour among females 12-34 and grabbing a boffo 26 share in female teens.