The 33-year-old Serb has been the top-ranked player at the end of a season five times: in 2011, 2012, 2014, 2015 and 2018. He shares that mark with career rivals Roger Federer and Rafael Nadal

The World No. 1 reached the semi-finals in Toronto and will next face Russian Karen Khachanov, who beat Robin Haase 6-3, 6-1