By Pritha Sarkar LONDON, June 30 (Reuters) – Wimbledon’s routine of no play on the middle Sunday needs changing so that player interests are preserved and competitors do not have to endure best-of-five-set matches on successive days, said Novak Djokovic. Two days of rain, on Saturday and Monday, at the grasscourt major have thrown the schedule into disarray and left players like Australian Open champion Stanislas Wawrinka facing the prospect of three best-of-five-set matches in three days to reach the semi-finals. Top seed Djokovic is lucky to have avoided the mayhem as he was not scheduled to play on Saturday and was given Centre-Court billing on Monday – with his match played under a closed roof. While those players in the top half of the men’s draw, which include Djokovic and defending champion Andy Murray, are already through to the quarter-finals, fifth-seeded Swiss Wawrinka is still in the last 16 having won his third-round match on Monday.