World number one Ashleigh Barty brought the WTA season to a close with victory in the WTA Finals in Shenzhen.

The Australian has emerged on top after what has been a dramatic and compelling year that has again seen four different grand slam champions and the emergence of a teenage superstar in Coco Gauff.

Here, the PA news agency picks out five things we have learned from the WTA season.

The future is bright

It was not so long ago that Petra Kvitova was the only player born in the 1990s to win a grand slam title. This year she was the oldest player at the WTA Finals. Simona Halep, a year younger at 28, was the oldest slam winner, with the other titles won by 23-year-old Barty, 21-year-old Naomi Osaka (now 22) and 19-year-old Bianca Andreescu. It is not hard to see that trio – all with their own identities on and off the court – along with 15-year-old Gauff dominating the sport for years to come.

Going loco for Coco

One of the most exciting things about the new stars of the game is how their games compare and contrast. Power tennis has largely defined the generation now heading into or already in their 30s but what is emerging now – Osaka aside – is a different picture. None of the young players are afraid to come to the net. Barty is probably at her best there while Andreescu has an all-round game that is staggering in its lack of weakness. There is also Marketa Vondrousova, who drop-shotted her way to the French Open final, and Belinda Bencic, another complete all-rounder.

End nigh for Sharapova?

The Williams sisters and Maria Sharapova have been the female players to have transcended the sport over the past 20 years. Venus will turn 40 next year but it seems increasingly probable that Sharapova, a relative youngster at 32, could be the first of the trio to retire. The Russian managed just eight tournaments this year, winning eight matches in total, only two since January. Sharapova's right shoulder simply does not appear able to withstand the demands of the sport and, although she has been planning for 2020, the Russian is now ranked down at 136.