The candidates have filed their nomination papers on June 30 and who's running where is now official.

If you are feeling overwhelmed by all the General Election information, here are the top five constituency battles to watch, ranked.

#1: East Coast GRC

People's Action Party (PAP) vs Workers' Party (WP)

PAP: Heng Swee Keat, Maliki Osman, Cheryl Chan, Jessica Tan, Tan Kiat How

WP: Terence Tan, Nicole Seah, Kenneth Foo Seck Guan, Dylan Ng, Abdul Shariff

Heng, who has been with Tampines GRC for close to 10 years, will now be anchoring the team in East Coast.

Heng later explained that his move from Tampines GRC to East Coast GRC was made after a discussion with Prime Minister Lee Hsien Loong, saying that the PAP "cannot afford a gap in East Coast in these uncertain times.

WP has been contesting at East Coast GRC since 2006.

In 2011, they gained 45 per cent of the votes, with Gerald Giam becoming one of the three non-constituency members of parliament (NCMP).

In 2015, they gained 39 per cent of the votes, the closest any opposition team came to claiming a GRC outside of Aljunied.

The current two WP NCMPs - Leon Perera and Daniel Goh - are from the 2015 East Coast GRC team.

The party traditionally sends its B-team to contest in East Coast.

This election, the WP East Coast team features familiar faces, such as Nicole Seah who previously contested in 2011 under the National Solidarity Party, and Terence Tan, who previously contested in Marine Parade in 2015.

Tan is also WP Deputy Organising Secretary and Central Executive Committee (CEC) member.

Pritam Singh, WP chief, said in a doorstop on June 30 that PAP's decision to put DPM Heng as the anchor minister for East Coast sends an "important signal" that they take the challenge in East Coast seriously.

#2: West Coast GRC

PAP vs PSP

PAP: S Iswaran, Desmond Lee, Foo Mee Har, Ang Wei Neng, Rachel Ong

PSP: Tan Cheng Bock, Leong Mun Wai, Jeffrey Khoo, Hazel Poa, Nadarajah Loganathan

West Coast GRC, which was formed in 1997, has traditionally been a PAP stronghold. In 2015, PAP won 78.57 per cent of the votes against the Reform Party.

This year, it sees a challenge from PSP, a newly-formed party led by Tan Cheng Bock. Tan is a former presidential runner-up who lost narrowly by 0.35 per cent.

Tan has previously served as MP for Ayer Rajah from 1980 to 2006 (before the ward was merged) and was the doctor in the area, and believes that this will give PSP an advantage in the election, CNA reported.

Lee, minister for social and family development, will now be competing at West Coast. He was formerly from Jurong GRC.

This means that the PAP team will see two ministers, one of the two GRCs (Tanjong Pagar is the other GRC) with two ministers.

#3: Aljunied GRC

PAP vs WP

WP: Pritam Singh, Sylvia Lim, Faisal Manap, Gerald Giam, Leon Perera

PAP: Victor Lye, Chua Eng Leong, Shamsul Kamar, Chan Hui Yuh, Alex Yeo Sheng Chye

The WP line-up sees two new teammates – Leon and Giam – who were previously from East Coast GRC, taking the place of Low Thia Khiang and Chen Show Mao. This will be the first election that Low will not be contesting in since 1988.

Pritam had announced in a press conference that three members, Low, Chen, and Png Eng Huat, would be stepping down.

From the PAP team, Lye, Shamsul and Chua went up against the incumbent WP in 2015.

Aljunied GRC, which has been held by the WP since 2011, won narrowly in 2015 with a vote share of 50.95 per cent. It remains to be seen if they can defend the GRC during this election.

#4: Bukit Batok SMC

PAP vs SDP

PAP: Murali Pillai

SDP: Chee Soon Juan

Murali Pillai is the incumbent PAP candidate for Bukit Batok SMC. He was a candidate with Aljunied GRC in 2015, and there was word that he did really well in his Paya Lebar constituency against Chen Show Mao, which Chen disputes.

Chee Soon Juan, who is SDP sec-gen, led a team contesting at Holland-Bukit Timah in 2015, garnering 33.4 per cent of the votes.

During the 2016 by-election, however, he went up against Murali. Chee garnered 38.8 per cent of the vote.

Exchanges between Chee and Murali have been widely reported in the past week, starting with Chee taking issue with the delays in estate improvements, saying that being an MP should be a full-time responsibility.

Murali then spelled out some plans that he has for the estate in response, ST reported. 

#5: Sengkang GRC

PAP vs WP

PAP: Ng Chee Meng, Lam Pin Min, Amrin Amin, Raymond Lye

WP: Jamus Lim, Raeesah Khan, He Ting Ru, Louis Chua

Sengkang GRC is a new GRC made up of the Sengkang West and Punggol East wards, as well as a portion of Pasir Ris-Punggol GRC.

In 2015, WP contested both Sengkang West and Punggol East SMCs. Both constituencies are no longer on the electoral map.

Labour chief Ng Chee Meng, previously part of the PAP team that won the Pasir Ris-Punggol GRC in 2015, is now helming PAP's Sengkang team. Amrin Amin was previously from Sembawang GRC.

WP's Sengkang team sees newcomers, including 26-year-old social entrepreneur Raeesah Khan and Harvard graduate and economics professor Jamus Lim.

Cambridge-educated lawyer He Ting Ru, who previously ran as a candidate in Marine Parade GRC in 2015, will be a familiar face.

Top image from MCI, PSP/FB, Syahindah Ishak, SDP/FB & Zheng Zhangxin.