The 20-time Grand Slam champion looked in all conquering mood in his tournament opener and brushed aside Rublev in straight sets with the scoreline reading 6-3, 6-4 in one hour and 18 minutes.
"It's important to start well, of course, for the confidence, and winning straight sets helps," said Nadal after his dominant win over his Russian opponent. "I played solid with my serve. I didn't suffer much, and that helps to play more relaxed on the returns," he added.
Nadal has another stiff challenge up his sleeves in this highly competitive year end tournament as he takes on newly-crowned US Open champion Dominic Thiem in his second group match on Tuesday.
"I'm going to try to be ready for it," said Nadal "It's going to be a big challenge, but I really hope the victory of today could help me for that match."
The 2020 ATP Finals got underway with third seed Austrian Dominic Thiem overcoming a stiff resistance from Stefanos Tsitsipas and clinching a hard fought 3-set win (7-6 (7-5), 4-6 and 6-3 over the rising Greek tennis star.
Thiem overcame a bit of a scare in the first set as he turned around a 3-5 tie break deficit by winning four straight points and get into the lead.
"That was the silliest thing that ever happened to me," Tsitsipas said of his play while leading 5-3. "I had a ball over the net, and I decided to play forehand instead of a smash. I don't know what kind of decision that was, but it was not sure enough. It didn't take time. Just rushed."
World No. 1 Novak Djokovic, who ended the year as the number ranked player for a record equaling sixth time, will get his campaign under way in Group 'Tokyo 1970' taking in Argentine Diego Schwartzman on Monday.