The Spaniard, who drew level with Roger Federer on 20 grand slam singles titles when he won last month's French Open, needed just under 78 minutes to defeat Rublev 6-3 6-4 in London and claim a first opening win at the event since 2015.

Making his first appearance at the Finals, Rublev struggled on his serve and hit 22 unforced errors to Nadal's 11.

Nadal, who qualified for a record 16th consecutive year-end championships, broke in game six of the first set before seeing it out with a love service game.

Rublev has been the most successful player on the Tour in 2020 in terms of titles, winning five, but he cut a defeated figure as soon as Nadal went a break up at the start of the second set.

The world number eight eventually settled into his serve but Nadal was impervious to a comeback, seeing out the victory with his second match point when Rublev returned long.

"I think it has been a positive start for me," he said. "Always, the first match is very tricky.

"Here, every match is difficult, you play against the best of the best so [I am] very happy. [I am] sorry for Rublo but I wish him the very best for the rest of the tournament. He had an amazing season even under these very difficult conditions. We had the season and he was able to win a lot of titles so it's an important victory for me."

Nadal faces Dominic Thiem next, the US Open champion having started his tournament with a three-set win over Stefanos Tsitsipas.