Australian Open champion Novak Djokovic swept past Belgium's Oliver Rochus 6-3, 6-2, 6-2 to give Serbia a commanding 2-0 lead after Friday's opening singles in their Davis Cup first-round series.
On Saturday, Serbia can advance to the next round with a victory in the doubles.
Earlier on Friday, Viktor Troicki fought back from two sets down to beat David Goffin 1-6, 3-6, 7-6 (5), 6-4, 6-4 and give Serbia their first point.
Despite the switch from the fast hardcourt conditions in which he won his third straight Australian open on Sunday to the slow, sticky indoor clay of the Spiroudome, Djokovic dismissed the 127th-ranked Rochus without a hitch.
He had complained about the clay court as being dangerous because it was too wet, but it never showed in his game, as he turned the match into a demonstration of skill and stamina.
"I can't believe what I'm experiencing... I told myself I had to take advantage of this opportunity that was given to me"
Argentine Carlos Berlocq
Belgium had a chance to make it an exciting weekend when their top player, the 50th-ranked Goffin, easily won the first two sets and only had to hold serve deep in the third for victory. But he buckled under the pressure, and Troicki came back to win the tiebreaker and had the better nerves to complete an unlikely comeback.
Argentina took a 1-0 lead over Germany in the first round of the Davis Cup when Philipp Kohlschreiber had to retire when leading 5-4 in the deciding fifth set, walking off a sweltering clay court with a leg injury to hand the match to Carlos Berlocq.
Berlocq won 3-6, 7-5, 2-6, 6-4, 4-5.
Kohlschreiber gave into the leg injury and temperatures hovering around 32 degrees Celsius (90F) in a 4-hour match in the Argentine capital.
"I can't believe what I'm experiencing,'' Berlocq said after beating Germany's top player.
"I told myself I had to take advantage of this opportunity that was given to me."
Argentina, which defeated Germany a year ago in the first round, is playing without its No. 1 player Juan Martin del Potro, who chose to focus on tour matches and skip this round of the Davis Cup.
Kohlschreiber had a chance to win the match in the fourth set, but failed to capitalise on three breaks points that would have had him serving for the match with a 5-3 lead.
The 14,000-seat stadium was one-third full with many Argentines away on holiday, put off by the heat or uninspired by a matchup without top-name players.
Juan Monaco faced Florian Mayer in the second match, while David Nalbandian and Horacio Zeballos are expected to face Tobias Kamke and Christopher Kas in doubles on Saturday.
Reverse singles are Sunday.