If sources are to believed, singer Katy Perry has set her sights on Twilight starRobert Pattinson. The I Kissed A Girl singer, who separated from her husband Russell Brand last year, isapparently trying to flirt with Pattinson, who is in a serious relationship with his Twilight co-star KristenStewart, reported Showbiz Spy. The 27-year-old singer tried talking to the actor while he was enjoyingdrinks with Stewart at the Chateau Marmont hotel in Los Angeles. "As soon as Kristen went to the toilet,Katy made a beeline to flirt with Rob. Kristen was annoyed," a source said.