Nadal has not competed since playing doubles with Roger Federer in the latter's Laver Cup farewell match in London, which ended just after midnight on September 24.
Immediately after that, Nadal left London to go home to Mallorca and support his wife before the birth of Rafael jr who came into the world on 13 October.
36-year-old Nadal looked sharp in the first set which he won 6-3 and was also a break up in the second which he then lost in a tiebreak.
In the third, the air had completely gone out of Nadal, who was tired and made a lot of mistakes before the match ended just before midnight on Thursday night.
- It is true that in the last five months I have not spent enough days on the tour.
I need matches and to train with the guys, says Nadal, who gave himself up in the meeting with Paul, who lost a set against Leo Borg in the first round of the Stockholm Open recently.
Auger-Aliassime rewarded after the victory against Mikael Ymer
- I had a grip on the match in the second set with a break up, but I played a terribly bad game there.
I didn't deserve to win because I played so badly on the key balls, Nadal told the ATP tour.
However, he is looking forward to playing the ATP finals in Turin, where the eight best ranked will qualify, in two weeks.
- I will fight to be at a higher level then, says Nadal.
A couple of hours after the victory against Mikael Ymer, Felix Auger-Aliassime could rejoice at having secured a place in the ATP playoffs as other results went his way.
The Russian Andrej Rublev was also ready for the finals on Thursday evening.
Interesting statistic from the meeting with Ymer was that Auger-Aliassime won four of his five break points but saved 14 of 17 he faced.