It has been no secret that Rafael Nadal is enjoying his tennis again.
Before winning his 16th grand slam title at the US Open last month, the Spaniard said it was the fact he was healthy again, after years of knee and wrist problems, that gave him the most satisfaction.
"For me, more than winning grand slams or not - of course, if I win, I will be more happy - but it is about being healthy and feeling well and competitive," he said.
It has been a great year for Nadal. Back as a grand slam winner at the French Open, and then also at the US Open, while also regaining the world No 1 spot.
He is back in action on the ATP Tour this week at the China Open, and while the season is beginning to wind down, the world No 1 can still achieve a lot in the remaining two months.
There are no more majors at stake in 2017, but there are a lot of ranking points, starting with the 500 event in Beijing.
Twelve months ago this was the start of Andy Murray's run to No 1 as he won four titles in a row, before winning the ATP World Tour Finals in London.
Murray's sequence of 25 wins in a row showed the value of playing well in the October and November competitions.
Now, Nadal already has the top spot after taking it from Murray in August. He also has a healthy lead of 1,960 ranking points over Federer.
But, a strong end to 2017 can cement him in the position and set him for a long reign deep into 2018.
Nadal ended his 2016 season early, after losing his first match at the Shanghai Masters, and he only has 135 points to defend between now and the end of the year.
Federer has no points to defend and there is a scenario, particularly if he wins the Masters events in Shanghai and Paris and then the World Finals, where he can still end the year as No 1.
But, that would involve Nadal's form falling away completely as well, and there is no sign of that at present.
Surprisingly, for a man who is the second most successful player in terms of major titles in the open era of tennis, Nadal is somewhat trailing the other two dominant players of his era, Federer and Djokovic, in terms of time spent at No 1.
Nadal has had 147 weeks at the top spot so far in his career. More than good you would say, and it is the seventh highest since the rankings were established in 1973.
But, Federer has had 302, and Djokovic 223, and both men have had longer periods as No 1 then Nadal ever has.
Federer had four years at the top between February 2004 and August 2008, while Djokovic had a run that lasted more than two years between July 2014 until last November.
Nadal's longest run is 56 weeks between June 2010 and July 2011.
If he ends the year strongly it will set him for a good chance of being No 1 for a long part of 2018 at least and possibly matching or beating his previous longest streak at No 1.
Federer may end the year close to him, but his strong first seven months of 2017 mean he will have few points to gain in 2018 unless he commits to a clay court season.
Add in both Murray and Djokovic recovering from injuries and both starting next year outside the top 10, and the chances of any of the established players threatening Nadal's spot is limited.
So the chance for Nadal to establish himself at No 1 is there.
All he has to do is finish the season on a high, and how he gets on in Beijing will be a good indicator of if he can fully capitalise or not.