Novak Djokovic is encouraged by his progress after undergoing minor knee surgery less than three weeks ago but the seven-times Wimbledon champion said he will only play in the grasscourt Grand Slam next month if he is able to fight for the title. The 37-year-old picked up the injury to his right knee during his fourth-round win at the French Open and pulled out of the quarter-finals before having surgery on June 6, putting his Wimbledon and Olympic hopes in jeopardy. But the Serb, whose Paris Games spot was confirmed earlier this month, posted videos of his return to training on Instagram last week before arriving at the All England Club on Sunday and immediately ramping up his preparations.