The Serb faced stiff opposition in the first set but was able to dictate the match with his heavy serve.
When he got his first serve, he won 35 of 39 points.
- He was a number too big and there is not much to say about.
He was not at the top today and neither was I.
When you are not on top against him, you have to toil.
He showed many times out there why he is the best in the world, says Ruud, who jumped from the Stockholm Open last week when he qualified for the big tournament in Turin, to Eurosport after the match.
Ruud is the first Norwegian to take part in the tournament's 51-year history.
Aims to touch Federer's record
Djokovic has already secured the position as world number seven for the seventh time, which he is alone in.
He previously shared it with Pete Sampras.
Now he is going for a sixth tournament win in the ATP playoffs, which would touch Roger Federer's record.
Djokovic has not won the tournament since 2015 when he took his fourth title in a row.
In the first set, Ruud played offensively and disrespectfully and had an early break that Djokovic picked up again.
- I recovered well after the break.
There are difficult conditions here.
If you lose the serve, it is difficult to get back but I managed to hang in. I am very happy with how I handled the match, says Djokovic to ATP's website.