With the win, Nadal clinched his 80th ATP World Tour title and fifth victory of the year.
Nadal beat his Russian opponent 7-6 (3), 6-4 to register a straight set victory in a one side clash.
Since 2016, it is Sindhu's eighth loss in major finals.
India had a remarkable win against Argentina 2-1 in COTIF Cup 2018 held at Spain.
The match is expected to start around 12.30 PM (IST) on August 5, 2018, Sunday in Nanjing, China.
The only time India entered the semifinals of the Hockey World Cup event was back in Mandelieu, France.
India will face Ireland in the quarterfinals on Thursday.
Bajrang Punia won gold in 70 kg category. Pinki (55kg) was lone woman gold medallist for India in the event.
The IAAF Continental Cup is slated to be held from September 8 to 9 in Ostrava, Czech Republic.
Last month, Chennai's 12-year-old Praggnanandhaa became the world's second youngest chess grandmaster.