SINGAPORE - The first woman to attain the rank of brigadier-general in the SAF, Ms Gan Siow Huang, 46, a first-time PAP candidate, is set to do battle alone in the new single-seat ward of Marymount.

She will go head to head with Dr Ang Yong Guan, 65, of the Progress Singapore Party, the opposition party led by former PAP MP Tan Cheng Bock.

Both have been confirmed as candidates for the general election, after their nomination papers were filed at Deyi Secondary School, the nomination centre for Marymount SMC, on Tuesday (June 30).

It is a new constituency carved out of Bishan-Toa Payoh GRC, and it has 23,444 voters.

Ms Gan made history in 2015 when she became the first woman brigadier-general in Singapore.

She served in the military for more than 25 years, beginning as an air traffic controller and rising through the ranks to command Singapore's four airbases, the largest formation in the Republic of Singapore Air Force.

She left the Singapore Armed Forces in March and is now deputy chief executive of the National Trades Union Congress' Employment and Employability Institute.

Ms Gan is married with three daughters, aged eight, 13 and 17. She had earlier been expected to stand as part of the Bishan-Toa Payoh GRC team led by Defence Minister Ng Eng Hen.

Her opponent, Dr Ang, a psychiatrist, previously stood in the 2011 General Election as a Singapore Democratic Party candidate in Holland-Bukit Timah GRC, and in 2015 under the banner of the Singaporeans First party in Tanjong Pagar GRC.

Prime Minister Lee Hsien Loong said on Monday that some among the People's Action Party's 27 new faces have the potential to become political office-holders, but who eventually does will depend on their performance at the polls and - if elected - as MPs.

In 2011, Dr Amy Khor and Ms Grace Fu became the first PAP women candidates in some 20 years to be fielded in single-member constituencies.

Both have fared well at the polls, winning more than 70 per cent of the votes in the 2015 election.