PARIS – World number 1 Novak Djokovic tightened his grip at the top of the ATP rankings published on Monday after his straight sets Italian Open win over Roger Federer. The Swiss, defeated 6-4, 6-3 by the Serb champ on Sunday, remains second ahead of Scot Andy Murray. Rafael Nadal, knocked out in the quarter-finals in Rome, sits on seventh just behind Canadian Milos Raonic , who dropped two places. As a result Tomas Berdych of Czech Republic and Kei Nishikori of Japan moved up to fourth and fifth place respectively. ATP Rankings: 1. Novak Djokovic 13,845 pts, 2. Roger Federer 9,235, 3. Andy Murray 7,040, 4. Tomas Berdych 5,230 (+1), 5. Kei Nishikori 5,220 (+1), 6. Milos Raonic 4,800 (-2), 7. Rafael Nadal 4,570, 8. David Ferrer (ESP) 4,490, 9. Stan Wawrinka (SUI) 3,845, 10. Marin Cilic (CRO) 3,325.