Traditionally, Single-Member Constituencies (SMCs) are popular battlegrounds, but the fight is not likely to be equally intense in all three of the new ones coming up for contest in the next general election.
Fengshan and MacPherson were carved out of the two Group Representation Constituencies (GRCs) where the People's Action Party (PAP) won by the slimmest margins in the 2011 election.
In contrast, Bukit Batok came out of the GRC where the PAP saw its second-best performance - outdone only by the GRC led by Prime Minister Lee Hsien Loong.
Before PM Lee said last week that the average GRC size would be reduced, PAP activists in Jurong GRC had barely considered the possibility of a boundary change, let alone an SMC being carved out of it.
"It was not on our radar," confessed the ward's MP David Ong.
Cautiously optimistic about the prospect of going it alone, Mr Ong said: "It will be an interesting and humbling experience. But I think the work will remain basically the same."
National University of Singapore associate professor Hussin Mutalib, however, raised the possibility that Speaker of Parliament Halimah Yacob, an MP for Jurong GRC, could be fielded in the single-seat instead.
Such a move would be "a good test" of the PAP's long-held view that the Chinese-majority electorate will not vote for candidates from the minority communities, he said.
The PAP won 67 per cent of the vote in Jurong GRC in 2011, against the National Solidarity Party (NSP).
The margin has not deterred at least one opposition politician, Mr Goh Meng Seng, who is the founder of the new People's Power Party, from expressing interest in contesting the new SMC.
Located in the west of East Coast GRC and bordering Workers' Party-held Aljunied GRC, Fengshan seems a natural WP target.
But political observer Lam Peng Er, senior research fellow at NUS' East Asian Institute, does not rule out a three-cornered fight.
"I'm not quite sure if the opposition parties would be able to avoid a three-cornered fight, it really depends on how they cut their deals," he said, highlighting the Singapore Democratic Party and Singaporeans First party (SingFirst) as possible contenders.
East Coast GRC saw the PAP's worst winning performance in a GRC in 2011. It got 54.8 per cent of the vote against the WP.
Current MP Raymond Lim stepped down as transport minister after the last election.
Asked if he would be fielded again, Mr Lim said: "This is for (the) party to decide. As it is, I am still actively working with a dedicated team of activists to serve our residents whose lives have become very much a part of mine."
But political observer and law don Eugene Tan thinks it's "unlikely" Mr Lim will get to stand again. "They could deploy an existing MP or put a new face."
MacPherson has a history of going it alone. It had been a single-seat constituency since its formation in 1968, except in the 1991 and 2011 elections when it was part of Marine Parade GRC.
"We're all very happy. We've been an SMC for a very long time and now we're going back," said PAP branch secretary Rosemary Lim. "We are all prepared and we're very sure that we'll do well," she added, pointing out that although Marine Parade GRC saw the PAP's second-worst win (56.7 per cent) in 2011, MacPherson was one of its better-performing wards.
One complication is that current MP Tin Pei Ling is due to give birth any time. However, party activists are going ahead under the assumption that she will run, Ms Lim said.
"She's still very gung-ho. It is up to the party's secretary-general but we all hope she'd run here."
Among those eyeing the SMC is SingFirst founder Tan Jee Say: "Of course, we are interested in contesting MacPherson. We've done a walkabout there but we want to work together with other parties."
• Additional reporting by Wong Siew Ying