A jubilant and relieved Serb Novak Djokovic said his mental strength was the key to winning Wimbledon for a second time, describing his five-set victory over the seven-times champion Roger Federer as the “best grand slam final I have played in my careerâ€. The Serb, who let slip a two-sets-to-one and 5-2 lead as Federer forced a deciding set, held his nerve in the final set to clinch a 6-7, 6-4, 7-6, 5 -7, 6-4 victory, giving him a seventh grand slam title and denying Federer what would have been a record eighth win at the All England Club. After string of Grand Slam final losses Djoker was happy to break the jinx with his gritty and gutsy performance.