* Bounces back from Wimbledon disappointment * Beats Nishikori for ninth straight time * Turns focus to Rio Olympics (Adds quotes, details) July 31 (Reuters) – World number one Novak Djokovic continued his dominance of Kei Nishikori with a 6-3 7-5 victory in the final of the Rogers Cup in Toronto on Sunday. After clinching his 30th ATP World Tour Masters 1000 title, Djokovic immediately started to turn his attention to something more elusive, an Olympic gold medal. In his first tournament since an upset third round loss to American Sam Querrey on the grass of Wimbledon four weeks ago, Djokovic returned to his winning ways and became the first four-time winner of the Rogers Cup.