In a few days, for the first time in three years, an engraver will begin inscribing a new name onto the Billie Jean King trophy. A name, which until recently, had not been associated with triumph all year.

So it was no wonder that after the biggest win of her career, the victor herself - for the second time in as many days - knew only to express herself in tears.

Even with her hand masking her face, there was no hiding the emotions that accompanied the "biggest day" of Agnieszka Radwanska's life.

She beat Czech Petra Kvitova 6-2, 4-6, 6-3 in 2hr 5min at the Singapore Indoor Stadium before a capacity crowd to win the singles title of the BNP Paribas WTA Finals Singapore presented by SC Global.

Said Radwanska, who was playing her first final in seven tries at the prestigious year-ender: "Just no words to say what I was feeling on court. I didn't really expect this at all, especially the beginning of the year, it was not great."

The Pole said that because just a few months ago, after a first-round exit at the French Open, she found herself "angry" and frustrated because nothing seemed to be working on court. But if anyone knows how to march on, it is Radwanska, who in almost every match on Tour, finds herself soldiering against a pack of power hitters.

She picked up two titles late in the year on the Asian swing, qualifying for Singapore in the nick of time - just two weeks before the tournament began.

Radwanska has made a comeback in the second half of the year in every way: For most of 2015, she has known only defeat against top-five players, yet in the last week, she has beaten the world No. 2, No. 3 and No. 5.

Said Radwanska: "Doesn't matter how you start. Matters how you end. You just fight until the end."

Before her victory last night, the last person to win the WTA Finals without having first found Grand Slam success was former world No. 1 Amelie Mauresmo. The Frenchwoman, who won in 2005, went on to bag the Australian Open and Wimbledon the following year.

Radwanska, a finalist at Wimbledon in 2012 and a semi-finalist at every edition since, has received powerful proof this week of what she is capable of in the future.

"For sure, (this victory) gives me more confidence," said the new year-end world No. 5. "Especially that in a Grand Slam, you also have to win and beat couple of top players in a row.

"I think here it's even harder because it's just eight of us and you don't have any first rounds to (get) used to the courts.

"But definitely a good start. I'll definitely try to do that next year."

Until then, she has other things on her agenda.

First, pose for photographers with her prized trophy at the Singapore Botanic Gardens today as the newest champion of the WTA Finals. Then, maybe a zip around a couple of malls in town.

Radwanska, who won US$2.05 million (S$2.8 million), said with a smile: " I think I deserve for some shopping as well, so I definitely do that."

Certainly she has earned it.