Angelique Kerber simply didn't have enough left in the tank by the time she got to the final of the WTA Finals at the end of October.

The Bremen-born 28-year-old lost in straight sets 6-3, 6-4 to Dominika Cibulkova of Slovakia. Still, that did little to dampen Kerber's spirits at the end of what was by far the best season of her career. Having entered 2016 as the 10th-ranked player, few could have predicted that she would have jumped nine places by September.

However, the year started well for the German, who is now based in the Polish town of Puszczykowo, where her grandparents live.

In the first tournament of 2016, in Brisbane, Kerber got all the way to the final, where she lost to Victoria Asarenka in the final.  She took this good form into the first Grand Slam of the season, the Australian Open, but it almost ended just about as fast as it started.

Match point in the first round

"I had more than one leg on the airplane home to Germany" said, when asked about how she felt as she trailed in the second tiebreak after having lost the first to the 64th-ranked Japanese player Misaki Doi in the first round.

 "When it was match point against me, I felt the impulse to turn it all around," she said.

Turn it around she did, and in Melbourne, she never looked back, reaching the final at the end of January, when she beat the world No. 1, Serena Williams 6-4, 3-6, 6-4 to become the first German woman to win a Grand Slam tournament since Steffi Graf won the 1999 French Open.

However, the third seed on the clay of Roland Garros would suffer a setback in Paris, being knocked out by Kiki Bertens of the Netherlands 2-6, 6-3, 3-6 in the first round of the French Open. 

"It will take me a few days to get over this," she said. "I'm very disappointed; this simply wasn't my clay season."

'Melbourne was no fluke'

She had got over it, though, by the next Grand Slam, Wimbledon, where she would face a rematch with Serena Williams in the final. This time the German would lose a hard-fought match 6-4, 3-6, 6-4. However, simply reaching the final, Kerber leapfrogged Garbine Muguruza and Agnieszka Radwanska, moving from No. 4 to No. 2 in the women's rankings.  

"I didn't lose this final, Serena won it," Kerber said. "I have shown that Melbourne was no fluke."

Looking to add an Olympic gold medal to her haul, Kerber also advanced to the final in Rio de Janeiro, but again she would be stopped, this time after being hampered by a shoulder injury in the first set. She roared back in the second, but 34th-ranked Monica Puig of Puerto Rico would go on to beat the German 6-4, 4-6, 6-1 to win Olympic gold.  

Even at the post-match press conference, Kerber found it difficult to conceal her disappointment.

"It isn't the medal I wanted, but it is silver," Kerber said. "I am sad but also proud. I left my heart on the court. But Monica played the game of her life."

After that, it was on to the Western & Southern Open in Cincinnati, where she lost another final, this time to Karolina Pliskova 6-3, 6-1.

Williams knocked off her perch

Going into the US Open, the question on everybody's minds was whether Kerber would be able to use the final Grand Slam of the season to unseat Serena Williams as the world No. 1. The German, though, consistently refused to comment on the situation, as she sought to stay focused on her performance. By the time she got to the final, she was already the de facto women's No. 1, after Serena stumbled out of the tournament in the semis. Kerber went on to beat Pliskova 6-3, 4-6, 6-4 to win her second Grand Slam, confirming that she deserved to the top spot.

In Singapore, several weeks later, Kerber looked strong for most of the tournament featuring the best eight women's players - except for Williams, who had pulled out due to a shoulder injury. Kerber sailed through the group stage and had little trouble with the winner of the previous year's tournament, Agnieszka Radwanska in the semifinals, before succumbing to Cibulkova in the final.

Change in mentality

Still, Kerber had come so far from where she had been almost exactly one year earlier. Having needed to win a single set against Lucie Safarova to reach the semifinals in Singapore in 2015, the German buckled under the pressure and was eliminated.  This setback sparked a key change in attitude.

"I was not playing so well in the big tournaments last year, so at the start of this year I wanted to be more focused on the big tournaments and the Grand Slams, making sure I had good preparations for those tournaments. That was my goal," she said.

She more than achieved this goal in 2016, but 2017 will bring a completely new challenge - defending her position atop the women's rankings.

And far from ending on a sour note, Angelique Kerber's 2016 drew towards a close with a couple of other highlights. In mid-November, Kerber won a Bambi media prize in the category of sports, but that was likely topped  by an invitation to have lunch with outgoing US President Barack Obama, during his farewell visit to Berlin a few hours earlier.

By the time the winners of the German male and female athlete of the year awards were announced in Baden-Baden in  mid-December it came no surprise that here too that on the women's side, Angelique Kerber was the only logical choice.