The top seed needed just 70 minutes to routinely beat Joao Souza 6-1, 6-1, 6-1 in their first-round match at the US Open 2015 on Monday.
Defending champion beat German Philipp Kohlschreiber in two hours and two minutes on Monday to reach the second round.
Novak began his quest for a first Roland Garros crown with a 6-2, 7-5, 6-2 victory over 87th-ranked Jarkko Nieminen on Tuesday.
Novak and Viktor both won on the opening day at Kraljevo Sports Centre to give Serbia a 2-0 lead over Croatia going into Saturday’s doubles.
Kraljevo, Day 1: 13.00 CET Novak Djokovic (SRB) vs Mate Delic (CRO), followed by Viktor Troicki (SRB) vs Borna Coric (CRO).
The top seed opened his bid for a fifth Dubai Duty Free Tennis Championships title with a 6-4, 6-4 victory over Vasek Pospisil on Tuesday.
World no.1 opened his Australian Open campaign with a 6-3, 6-2, 6-4 win over qualifier from Slovenia Aljaz Bedene (116) on Tuesday.
Novak successfully started his 2015 season in singles on Tuesday with a convincing 6-2, 6-1 win over Dusan Lajovic at the Qatar ExxonMobil Open.
Nole moved to 20-0 at the China Open with a 6-2 6-1 win over Spaniard Guillermo Garcia-Lopez on Tuesday.
The top seed closed out a routine 6-1, 6-2, 6-4 win over world no.79 Diego Schwartzman to advance into the second round of the 2014 US Open on Monday night.