It's fair to say that no one really gave Agnieszka Radwanska any realistic chance of winning the recent WTA Tour Finals. She hadn't even qualified for the finals until the last couple of weeks. A late push for qualification saw her win the title in Tokyo.
October was very productive for her. A semi final in Beijing was followed by the title in Tianjin. That was enough for her to qualify but it was thought that she had left herself way too short of recovery time to have any impact at the Finals.
The Tour Finals are, in theory at least, fought out by the top 8 seeds at the end of the regular season. This year however the world number one, Serena Williams, had withdrawn due to injury.
The 8 players are split into the White Group and the Red Group. Each player plays the other 3 players in their own group with the top 2 in each group moving forward to the semi finals
Radwanska found herself in the same group as top seed Halep, Sharapova and also the US Open winner Flavia Pennetta.
Her first match was against Maria Sharapova. Before the match Radwanska was given a slight chance as Sharapova had been injured and had played just 1 match since the US Open in August. Much to the surprise of most people, Sharapova was not rusty and played at a high level from the start.
Radwanska stood her ground though and took the opening set. Sharapova levelled at one set all. Radwanska went a double break behind in the deciding set but managed to get one of the breaks back. As Sharapova served for the match for the second time Radwanska had two break points but couldn't convert either of them
Radwanska's second match was against the US Open champion, Flavia Pennetta. Radwanska started well and served for the first set. She wasn't able to hold serve and the set went to a tie break which the Italian Pennetta won. A tight second set also went to Pennetta and Radwanska's hopes of reaching the semi final seemed to have disappeared.
By the time Radwanska was due to play top seed Simona Halep in her third match, other results meant that she needed to win a set to keep her chance of a semi final place alive.
Radwanska's serve was broken in the very first game and the writing was on the wall for another defeat. However she wasn't ready to go home just yet. She fought back and in the sixth game Radwanska managed to get the break back. The set went to a tie break.
Halep took a 5-1 lead in the tie break but incredibly, Radwanska managed to win the next 6 points to win the set. Halep's spirit was broken and having held serve in the opening game of set 2, Halep lost the next 6 games. Radwanska had come back from the brink of elimination to take an unlikely semi final place!
In the semi final she was up against Spain's Garbine Muguruza. They had played 4 times in the 2015 season and Muguruza had won them all. Three of the matches had gone to a deciding set. Muguruza had won all her matches en route to the semi finals. She had also been in the doubles tournament which will have drained her energy.
When Muguruza took their opening set in a tie break I think everyone expected her to go on to meet Sharapova in the final. Radwanska had other ideas. Poland's top player took a 4-0 lead in the second set. Muguruza got one of the breaks back but Radwanska would break once again to take the match into a third set.
In the deciding set it was again Radwanska who took the early advantage. She raced into a 3-0 lead. She couldn't hold onto that break though and Muguruza fought back to 4-4. The momentum seemed to be with the Spanish player but as Muguruza served to take the set into another tie break Radwanska stepped up the pressure to break serve and take her place in Sunday's final.
The other semi final also didn't go as expected. Sharapova had won all her matches up to that stage and her opponent, Kvitova who has been struggling with Mononucleosis, was expected to be fatigued. Kvitova showed no signs of that fatigue though and won that match in straight sets.
So we had the final that no one expected. Both Radwanska and Kvitova had won just one of their 3 group matches and many have criticised the Round Robin format for this reason. I'm sure neither player was worrying about that as they took to the court on Sunday.
Going into this match they had played each other 8 times. Kvitova led 6-2 but both Radwanska's wins had come at year end Tour Finals.
Radwanska made the perfect start and broke the Kvitova serve in the very first game. She increased her advantage in the 5th game and that was more than enough to take the opening set.
The second set started in exactly the same way with Radwanska getting a vital break in the opening game. However Kvitova would break back in the 6th game and broke again in the 10th to take the final into a deciding set.Kvitova must have been confident that she had wrestled the momentum from Radwanska and in fact she broke in the first Radwanska service game for a 2-0 lead.
Radwanska wasn't behind for long and levelled the set at 2-2. Radwanska then took control with a break of serve. The last 5 games of the match would see 4 breaks of serve and it was Radwanska who ran out the winner.
Her 6-2, 4-6, 6-3 win gave her one of the most unlikely titles in the Tour Finals for many years. It will raise concerns over the Round Robin format from a purely tennis point of view but for entertainment value it keeps things interesting right to the end!