Wozniacki showed the form which took her to comprehensive victories in her opening group matches, although she suffered a defeat yesterday, having already qualified for the last four.

The Dane was forced to battle in the opening set against the Czech Republic’s Karolína Plíšková, but eventually edged a tie-break 11-9 at the Singapore Indoor Stadium.

Plíšková was unable to battle back into contest as the 25-year-old saw her serve broken by Wozniacki.

It allowed Wozniacki to wrap up a straight sets 7-6, 6-3 victory to advance to the final of this season-ending tournament for the first time since 2010.

The result prevented Plíšková from having a chance of securing the world number one ranking, with the Czech needing to have won the tournament to achieve the feat.

Romania's Simona Halep will, therfore, hold onto the world number one ranking into 2018. 

Wozniacki is scheduled to face Williams in the final after the American came from a set down to beat France’s Caroline Garcia.

Garcia claimed the opening set on a tie-break only for Williams to battle back to dominate the final two sets and triumph 6-7, 6-2, 6-3.

The result saw Williams become the oldest player to reach the final of the tournament, the 37-year-old surpassing Martina Navratilova.

The American was 36 when she reached the final in 1992, where she was beaten by Monica Seles, then representing the Yugoslavia.