London: Novak Djokovic, Roger Federer and Rafael Nadal are set to tighten their private stranglehold on Wimbledon as rivals struggle to keep afloat as they bid to dethrone the sport's A-list stars.

World No. 1 Djokovic is the defending champion and chasing a fifth title at the All England Club. Federer, promoted to second seed, can win a ninth crown while two-time champion Nadal is seeking to complete a rare back-to-back Roland Garros-Wimbledon double.