SINGAPORE - The coming general election will be the most hotly contested since 1965, with eight opposition parties and a handful of independents putting up a fight for all 89 seats in Parliament.

Three single-member constituencies (SMCs) - Bukit Batok, MacPherson and Radin Mas - will witness three-cornered fights.

Some group representation constituencies (GRCs) will also be closely watched.

The closest battles are expected to be fought mostly in the north-east and east of Singapore, between the People's Action Party (PAP) and the Workers' Party (WP).

Here is our list of the five hottest seats to watch in the 2015 General Election:

1. Aljunied GRC

How many seats being contested: 5

Who are the incumbents: WP party chief Low Thia Khiang, party chairman Sylvia Lim, Mr Chen Show Mao, Mr Pritam Singh and Mr Muhamad Faisal Abdul Manap.

Who are the challengers: PAP four-term MP Yeo Guat Kwang, Mr Victor Lye, Mr Chua Eng Leong, Mr K. Muralidharan Pillai and Mr Shamsul Kamar.

History: Formed in 1988 as a three-member GRC, expanded to four members in 1991 and then to five in 1997. Uncontested in two (1991 and 2001) of six general elections.

Which are the wards in the GRC: Bedok Reservoir-Punggol, Paya Lebar, Eunos, Serangoon and Kaki Bukit.

How many voters: 148,142.

Voter profile: 23 per cent live in private housing, 77 per cent in public housing; 75.4 per cent are Chinese, 13.4 per cent Malay and 8.6 per cent Indian.

How residents voted in GE2011: The WP team won with 54.7 per cent of the votes against a PAP team led by former foreign minister George Yeo, and also including Ms Lim Hwee Hua, Ms Cynthia Phua, Mr Zainul Abidin Rasheed and Mr Ong Ye Kung.

Why it's hot: Aljunied is the first multi-seat constituency to be won by a party other than the PAP since GRCs were introduced in 1988.

For this election, the PAP has deployed a team led by four-term labour MP Yeo Guat Kwang, and mentored by former PAP chairman and Cabinet Minister Lim Boon Heng, to take on WP's "A" team.

Pundits are watching closely if the ongoing controversy over WP's management of the Aljunied-Hougang-Punggol East Town Council (AHPETC) will erode support for the opposition party.

2. East Coast GRC

How many seats being contested: 4

Who are the incumbents: PAP team comprising Manpower Minister Lim Swee Say, Senior Minister of State Lee Yi Shyan, Minister of State Mohamad Maliki Osman and backbencher Jessica Tan.

Who are the challengers: WP's Non-Constituency MP Gerald Giam, Mr Daniel Goh, Mr Leon Perera and Mr Mohamed Fairoz Shariff.

History: Formed in 1997, it was first contested at the 2006 General Election.

Which are the wards in the GRC: Changi Simei, Siglap, Bedok and Kampong Chai Chee (includes Pulau Ubin and Pulau Tekong).

How many voters: 99,118.

Voter profile: About 48 per cent live in private housing, 50.2 per cent in public housing.

How residents voted in 2011: The PAP team led by Mr Lim Swee Say garnered 54.8 per cent of the votes. They defeated a WP team comprising Mr Gerald Giam, Mr Png Eng Huat, Ms Glenda Han, Mr Eric Tan and Mr Mohamed Fazli Talip.

Why it's hot: East Coast was the worst-performing GRC won by the PAP in 2011. The GRC saw a nine percentage point drop in its winning margin compared to the 2006 election.

The GRC has since been downsized from five to four members, with its Fengshan ward hived off.

Mr Gerald Giam, who was part of the WP team contesting East Coast in 2011, will lead it this time with a new line-up. Will it be second time lucky for WP?

3. Fengshan SMC

Who are the candidates: PAP's Ms Cheryl Chan and WP's Mr Dennis Tan .

History: It was first created in 1984 and held by PAP's Dr Arthur Beng for two terms before it was absorbed into the now-defunct Bedok GRC in 1991. It then became part of East Coast GRC in 1997.

How many voters: 23,427.

Voter profile: 30 per cent live in private housing, 70 per cent in public housing.

How residents voted in 2011: The ward was previously part of East Coast GRC.

Why it's hot: Long-time grassroots volunteer Cheryl Chan is the first new PAP candidate to be fielded in a new SMC in nearly three decades, since the GRC system was introduced in 1988.

There has been speculation that Fengshan was the reason for East Coast's lacklustre performance at the 2011 polls. The GRC's anchor minister Lim Swee Say, however, has dismissed it as untrue.

Fengshan is also where the "orh luak" or oyster omelette analogy originated after WP chairman Sylvia Lim got pundits guessing that she might be fielded there. And it all started because she posted an Instagram picture of her tucking into the local dish at a food centre in Fengshan.

4. Punggol East SMC

Who is the incumbent: WP's Ms Lee Li Lian.

Who is the challenger: PAP's Mr Charles Chong.

History: Created in 2011 after it was carved out from Pasir Ris-Punggol GRC.

How many voters: 34,466.

Voter profile: Not available.

How residents voted in 2011: PAP's Mr Michael Palmer won with 54.5 per cent in a three-cornered fight with WP's Ms Lee Li Lian (41 per cent) and Singapore Democratic Alliance's Desmond Lim (4.5 per cent).

How residents voted in the 2013 by-election: Ms Lee was elected with 54.5 per cent of the votes in a by-election after Mr Palmer stepped down following revelations of an extra-marital affair. She beat PAP's Dr Koh Poh Koon (43.7 per cent), Reform Party's Mr Kenneth Jeyaretnam (1.2 per cent) and Mr Lim of the SDA (0.6 per cent).

Why it's hot: The PAP will be banking on experience to win the day with long-serving MP Charles Chong being deployed to try and wrest control of the ward from Ms Lee.

Mr Chong was most recently MP for the now-defunct Joo Chiat SMC.

Punggol East is part of the troubled AHPETC, which has come under scrutiny for its mismanagement of town council funds. Will there be a knock-on effect in Punggol East?

5. MacPherson SMC

Who is the incumbent: PAP's Ms Tin Pei Ling.

Who is the challenger: WP's Mr Bernard Chen and Mr Cheo Chai Chen, who is contesting under the National Solidarity Party (NSP) banner.

History: First created in 1968 and merged into Marine Parade GRC 1991. Carved out in 1997, then re-absorbed by Marine Parade in 2011.

How many voters: 28,511.

Population profile: 9.3 per cent live in private housing, 90.7 per cent in public housing; 74 per cent are Chinese, 12.2 per cent Malay and 11.2 per cent Indian.

How residents voted in 2011: The ward was part of Marine Parade GRC in the 2011 election.

Why it's hot: PAP's Ms Tin, who was put in charge of the MacPherson ward when it was part of the Marine Parade GRC, has had a rough start. Ms Tin, the youngest PAP candidate in the 2011 election, came under criticism for her inexperience, among other things.

But the ground appears to be sweeter for her this time round, after four years of serving the residents.

All eyes will be on how she fares standing on her own in a three-cornered battle against candidates from the WP and NSP.