The 36-year-old says he is looking forward to facing the 58th-ranked Zhang in Sunday's group tie

Defending champions expect stiff competition on the return of his Spanish rival

World number one Djokovic takes responsibility for Serbia’s Davis Cup semi-final exit

Serbia lose 2-1 after world number four defeats world number one 6-2, 2-6, 7-5 to reach finals

Tennis great steers Serbia into Davis Cup semi-finals with 2-0 win over Great Britain

World number one says ‘one of the best seasons I’ve had’ as he beats Italian 6-3, 6-3 in Turin

Italian beats Rune to seal Serbian world number one’s ATP Finals ticket to semis

World number four defeats Serbian 7-5, 6-7 (5/7), 7-6 (7/2) to become the first Italian to reach ATP last four

Serb secures year-ending world number ranking after beating Rune at ATP Finals

World number one beat fifth seed 5-7, 7-6 (7/3), 7-5 to book final with unseeded Dimitrov