Murray has not won a grand slam since parting ways with Lendl in March 2014 after two years in which he won the 2012 Olympic gold, the 2012 US Open and the 2013 Wimbledon titles.
The two rekindled their partnership on Sunday and are already plotting to stop Djokovic, the first man since Rod Laver in 1969 to hold all four grand slam titles at the same time.
The Serb has won the French and Australian titles this year and victory at Wimbledon and the US Open in August would give him a calendar-year grand slam. Adding gold at the Olympics in Rio would see him seal the golden slam.
"To me there is a career grand slam, then all four in a row, next the calendar year grand slam and on the top the golden slam (including the Olympic gold medal). Djokovic has a chance to do that this year," Lendl told British media.
