It was a battle of the TV titans last night and no one walked out of the arena unscathed. First of all, CBS’ Survivor (2.4/7) returned for its 26th season Wednesday, but it did not come back strong. The 90-minute premiere of Survivor: Caramoan – Fans vs. Favorites was down 23% from last year’s winter debut, marking the series’ lowest-rated series premiere ever. About 8.96 million watched. Meanwhile, head-to-head with Survivor last night was that other seasoned reality heavyweight: Five weeks into its 12th season, American Idol (4.3/12) started its Girls Only Hollywood Week on Wednesday. Slipping 7% from last week’s show, last night’ marked the lowest adults 18-49 Idol Wednesday since July 10, 2002, and its least-watched Wednesday since August 7, 2002 — from the show’s first season. Still, Idol was the night’s most-watched show with 13.37 million tuning in.