A floundering Novak Djokovic should seek advice from evergreen Swiss maestro Roger Federer in order to rediscover his vintage self, the Serb's former Davis Cup coach Bogdan Obradovic said.
Djokovic has suffered a spectacular fall from grace since he captured his maiden French Open title last June for his 12th major honour, completing a career slam of winning all four of the world's top tennis tournaments.
"Given that Federer was able to return into the top 10 and win this year's Australian Open at the age of 36, I see no reason why Djokovic can't be the world number one again," Obradovic told Belgrade daily Blic on Sunday.
"Maybe Djokovic should talk to Federer. They are friends, they have known each other for a long time and the Swiss can certainly give him some good advice."
Having relinquished the top spot in the ATP rankings to Briton Andy Murray in November, Djokovic made a shock second-round Australian Open exit to Uzbek Denis Istomin followed by successive defeats to Australian Nick Kyrgios in Acapulco and Indian Wells.
The 29-year-old Serb also crashed out of the Monte Carlo quarter-finals on Thursday with a painful defeat by Belgian David Goffin after he threw away a 4-2 lead in the third set.
Obradovic, who steered Serbia to the 2010 Davis Cup title and the 2013 final during his 10-year spell in charge, made way in December for doubles specialist Nenad Zimonjic who has since appeared in a dual player-coach role.
Having advised Djokovic several times to restore meat to his diet, Obradovic stressed he believed that Djokovic's perceived loss of appetite on the court has come hand-in-hand with more hunger shown by rivals who have sensed blood.
"All other players seem to be galvanised against him while his own motivation appears to be inconsistent and shifting all the time," said Obradovic.
"He is not at his best, his serve keeps fluctuating as do elements in his game which really used to be at highest level consistently.
"However, it is difficult to play at such a high level indefinitely. Murray has a huge advantage in the standings but I am sure Djokovic will be back in contention for the top spot."