Image source, PA

What a fitting end to another fine year! Is this finally the time when the Next Gen break through?

I know, I know, we've asked this every year since about the year 20-something. But this feels different, doesn't it? Let's see what happens in 2020...

The season isn't completely over though... we have the not-so small matter of the inaugural Davis Cup finals in Madrid next week.

Andy Murray says the new format, which has been criticised by the likes of Roger Federer, Alexander Zverev and countless fans, should be given a chance. Who are we to argue with a Knight of the Realm?

if you return to the website/app tomorrow you will find an explainer piece on the new tournament which features 18 national teams including Great Britain.

And if you need a tennis fix tonight then head over here to have a go at our 'Who said what in 2019 quiz'.

Anything else? Nope, that's it. Thanks for your company on a thrilling ATP Finals weekend - and make sure join us in Madrid later this week! Hasta luego...

Matthew Henry
BBC Sport at the O2 Arena

Tsitsipas is still on court speaking to the world’s media. A group of rowdy fans with Greek fans have congregated in one corner of the stand and are chanting his name.

Image source, BBC Sport

And it is a double celebration for Pierre Hugues-Herbert...

I'm presuming Julia's startled look was because she didn't know PHH was going to announce it rather than she doesn't know she'd agreed to marry him...

Image source, Reuters

A little while ago, French pair Nicolas Mahut and Pierre-Hugues Herbert filled a gaping hole in their trophy cabinets by clinching their first ATP Tour victory in the doubles final.

The pair completed the career Grand Slam by winning the Australian Open title in January then had a bit of a tiff, Herbert saying he wanted to concentrate on his singles career, only to slope off with a few other doubles partners - including Britain's Andy Murray at Wimbledon - over the summer.

But like all unconditional relationships, they overcame the rocky patch, patched things up and have gone on to even better things.

After winning at home in the Paris Masters earlier this month, they have gone one better than last year's runners-up prize after beating Raven Klaasen and Michael Venus at the O2.

Image source, Getty Images

While Tsitsipas says he will mark the biggest victory of his career with a meal with his family and "some champagne", he's not the only one who will be celebrating tonight...

Surely it is a question of when not if Stefanos Tsitsipas wins a Grand Slam. Next year?

Just imagine the scenes in Melbourne - which has the biggest Greek population outside of Greece - if he does it there in January.

I hope the Aussie Open organisers are prepared for an influx of Greeks watching it on the big screen again...

What a year for Stefanos Tsitsipas.

THAT win over Roger Federer on his way to the Australian Open semi-finals.

THAT win over Rafael Nadal in the Madrid semi-finals. ON CLAY.

TWO titles in Marseille and Estoril.

And now this.

"This year was the best year I've had and I want to constantly improve," he says.

"Things were great this year and I beat some top-ranked players which gave me confidence and I've won matches in Grand Slams and Masters 1000s. I think I can do well in the Slams."

More from our Greek god, Stefanos the Great: "I can't sum up my emotions right now. It's amazing to be remembered as the 2019 champion. It is a dream come true and the best way to end this match.

"I did get nervous at some points in the match but I managed to forget about how I felt and I had momentum in the tie-break which was really tight.

"My fighting spirit and me constantly trying to push myself to do better got me there in the end."

On the backing of the Greek-dominated O2: "People turned this into a football stadium it feels so nice to have people chant my name. I can only thank those people who came from Greece."

Stefanos Tsitsipas's interviews are *almost* as delightful as his tennis matches.What a human.

Tsitsipas goes on, sweetly laughing in between musings. He can't believe it!

"It has been a rollercoaster, holding this trophy is amazing."

After saying thanks to his nearest and dearest, particularly dad/coach Apostolos, and a plug for the three-striped brand which sponsors him and Thiem, Tsitsipas turns back to the Austrian...

"I'm sure we are going to face each other more times in the future and I hope it works this way. We'll make a deal later!"

Here he is... Stefanos Tsitsipas, in that delightfully earnest and quirky way of his, takes the mic. Who knows where this will go and when it will end...

"I would like to start by congratulating Dominic. You have been an inspiration not only for me but many players around the world. This final we put on was magnificent, tennis is all about this."

Tsitsipas hoists the trophy into the air, bits of blue and silver tickertape landing in his tousled mane.

Speeeech!

The DJ presses play on a dubstep track, the ticker tape operative opens the cannon... that means Stefanos Tsitsipas is collecting a brand new bit of bling.

Dominic Thiem, as tradition dictates, is given the microphone first to make his runner-up speech.

Starting off with some lovely words about the man who has just beaten him...

"I really hope we are going to have some great finals in the future as well, I'm really looking forward to it," says the 26-year-old Austrian.

Hear, hear...

What I really loved was the embrace between Tsitsipas and Thiem at the net. The pair are good friends, the love and respect clear as Tsitsipas kissed his beaten opponent on the shoulder.

Where's that heart emoji?

One appearance, one win. If cheap Danish lagers did ATP Finals debuts...

Stefanos Tsitsipas is the SEVENTH man to win on his first appearance at the season-ending finale.

2018 ATP NextGen champion ---> 2019 ATP Finals champion

Stefanos Tsitsipas did his apprenticeship last year and has clearly learned from that experience. Nerveless!

Tim Henman
Former British number one on BBC Two

For the last tournament of the year to come down to a final set tie-break was fitting I think.

Thiem has been fantastic in final sets this year but it showed the resilience and maturity of Tsitsipas. He fully deserves the biggest title of his career.

Stefanos Tsitsipas on the biggest victory of his fledgling career: "I've no clue how I played so well in the second set, I think my mind was at ease and I didn't give him much opportunity to play.

"It was frustrating to play with so many nerves but I'm so relieved I managed to win!"

Boris Becker
Three-time Wimbledon champion on BBC TV

A superstar is born in my eyes, he is box office!