Leonardo DiCaprio was reportedly dumped by Gisele Bundchen for flirting with Sienna Miller, sources have claimed.The heartthrob actor was caught getting cosy with the stunning actress - who has had an on-off relationship with boyfriend Jude Law since he admitted cheating on her with his children's nanny - in a Los Angeles nightclub several weeks ago. Supermodel Gisele was said to have been so furious when she found out that she called off her tempestuous romance with Leo once and for all. A friend is quoted by Britain's The Sun newspaper as saying: "She was tired of Leo's flirting. The straw that broke the camel's back was none other than Sienna"Gisele is now rumoured to be dating Pamela Anderson's ex Kelly Slater, while Leonardo has been spotted out with his former lover Paris Hilton, who is currently dating Greek shipping heir Stavros Niarchos.Onlookers claim the pair were "deep in conversation" during a night out at the Hard Rock Hotel in Las Vegas.A witness is quoted by Britain's Daily Star newspaper as saying: "Leo looked like he was in his element chatting away to Paris. It was almost as though Paris was trying to give him advice on his love life"