WATCH: Jannik Sinner offered cake for 21st birthday, says he will save it for post-Cincinnati 2R win

Jannik Sinner got the cherry on top of his 21st birthday cake as he bested Thanasi Kokkinakis, 6-7(9), 6-4, 7-6(6), in the first round of the Cincinnati Open on his special day.

It took the Italian three hours and 15 minutes to dispose of the Australian in their first ever career encounter.

Sinner thus picked up his 37th win of the season (against 10 losses) and an actual cake to boot when he graced the Tennis Channel for a post-match interview.

After a brief chat with presenter Prakash Amritraj, Sinner was surprised with a cake, which he and Amritraj promised to partake of after his second-round win.

Sinner will next face Miomir Kecmanovic, who, for his part, eliminated recently crowned Montreal champ Pablo Carreno Busta, 1-6, 7-5, 7-6(4).

In the video, Sinner can be seen beaming after receiving the cake. The World No. 12 then quipped that he just had his fill of a chocolate-flavored one.

"I am going to be honest: I just ate and we have just had a cake, a chocolate cake. It's obviously very special to have this back," said Jannik Sinner.

Bantering with Sinner, former tennis player Amritraj said that they could have it instead once he wins his second-round match, to which the Italian promised to do so. They sealed their agreement with a high-five.

"We will do like this: if I win, I will come back and we will share our little piece of cake," said Jannik Sinner.

"Sometimes, I think back from where I started and where I am right now and, hopefully, I can be in the future; So it's always good to have these flashbacks a little bit" - Jannik Sinner

Jannik Sinner celebrates his 21st birthday with a win over Thanasi Kokkinakis at the Cincinnati Open

Jannik Sinner waxed nostalgic during his interview with Prakash Amritraj on the Tennis Channel.

Asked what was going through his mind on his 21st birthday given that he is still young and might not yet be disposed to reflect, Sinner said that he does do a bit of introspection. He revealed that he looks back at where he started, where he is at present and where he could be in the future.

"In Italy and Europe, the special birthday is when you make 18. Here, it's 21. So it is a little bit different. But sometimes, I think back from where I started and where I am right now and, hopefully, I can be in the future. So it's always good to have these flashbacks a little bit," said Jannik Sinner.

"With the choices I've made in the good, there may also be in the bad times, so it's always nice to think about that," he added.

But with all the contemplation brought about by his birthday celebration, Sinner said that he is happy where he is right now and that is being able to play tennis, which he loves.

"But as I said, I think I can be happy where I am right now. Obviously, it takes a lot of happiness in my mind that I can play tennis which I love and that, for me, right now, is the most important," said Sinner.