Novak Djokovic won both of his matches and booked a place in the final as the second leg of his Adria Tour got under way in Zadar, Croatia.
The Australian Open champion, who has organised the series of exhibition events, recorded victories over Pedja Krstin and Borna Coric on Saturday.
Last week in Belgrade, a costly defeat to Filip Krajinovic meant Djokovic missed out on a place in the showpiece.
Instead, Dominic Thiem was crowned champion after a final win over Krajinovic.
This time, though, Djokovic will be in the final having won both of his encounters in straight sets on day one.
In his opening match, Djokovic fell a break down and saved three set points before winning a tie-break against Krstin, ultimately claiming a 4-3 (7-3) 4-1 victory.
A comfortable 4-1 4-3 (7-1) triumph over Coric followed as he recovered from a brief mid-match blip when he fell two games behind early in the second set.
Russian Andrey Rublev was another player to earn a 100 per cent record thanks to wins over Marin Cilic and Danilo Petrovic.
Alexander Zverev lost two tie-breaks as he suffered a defeat to Petrovic in his first match, before bouncing back with a victory over Cilic in the last contest of the day, winning a decisive final-set breaker.
On Sunday, the last round of group-stage matches in the day session will be followed by the final in the evening.
Grigor Dimitrov, who was in Djokovic's group, withdrew after losing to Coric in the first match of the day.