Four men turned up with their forms at the Keming Primary School nomination centre in Bukit Batok yesterday.
But when nominations for the by-election closed at noon, only two were in the race to be MP of the single-member constituency (SMC).
People's Action Party (PAP) Bukit Batok branch chairman Murali Pillai, 48, was the first to turn up at the school when it opened to the public at 10.30am. Singapore Democratic Party (SDP) chief Chee Soon Juan, 53, followed soon after.
Supporters of both men - numbering several hundred in all - gathered at the school yard and its canteen to wait while Mr Murali and Dr Chee settled nomination matters in the school hall on the second floor.
Police had set up barricades in the yard - PAP supporters in white on one side, SDP supporters in red on the other. They carried party banners and umbrellas, to be unfurled once nominations ended.
There was a bit of a stir online when images showing an SDP banner being put up prematurely made the rounds. Dr Chee told reporters later that the banner was put up to try out the placement, and he was sure it was subsequently removed.
Shortly before the clock struck 11am, Uber driver Shirwin Eu, 32, rushed to the school with his papers. He arrived alone, and told reporters he was hopeful those at the nomination centre would help him.
No one did. Contenders need to have their nomination papers signed by a proposer, a seconder, and at least four assentors - who must be eligible voters for the seat.
Shortly after 11am, veteran opposition figure Kwan Yue Keng, 68, turned up. The retired sales manager, now a People's Power Party (PPP) member, said he had prepared his papers and the $13,500 election deposit, but would contest only if Dr Chee was disqualified.
"I'm ready to stand and fill in the gap. I'm here to prevent a walkover," he said, adding that the decision was made together with the SDP.
Veteran SDP member Jufrie Mahmood, who spoke to Mr Kwan, nodded in agreement, adding that he is a known figure in Bukit Batok.
Mr Kwan had contested twice in Bukit Batok as an SDP candidate when it was last an SMC, against the late Dr Ong Chit Chung of the PAP. He got 48.2 per cent of votes against Dr Ong in 1991, and 44.1 per cent of votes against him in 1988.
Both Mr Eu and Mr Kwan entered the nomination hall separately. The Elections Department said election officials had explained to Mr Eu and Mr Kwan the requirements and procedures for an individual to be nominated. They left without filing nomination papers.
PPP chief Goh Meng Seng later said on Facebook the party had prepared a candidate to prevent a walkover, as there were some concerns SDP had breached election rules.
He uploaded an image of a PPP election poster of Mr Kwan, saying: "Although PPP has withdrawn as SDP's nomination was done properly, I am still proud of my party's support team to be able to get all preparations done in such a short notice."
The only other person who had got the required political donation form was opposition veteran Abdul Rahim Osman, 59, who was in the Workers' Party (WP) team led by the late J.B. Jeyaretnam in then Cheng San GRC in the 1997 General Election. But on Tuesday night, he said he would not stand and was backing Mr Murali.
He told The Straits Times the decision was "in view of the wishes of the people of Bukit Batok SMC". "Murali has our support because he has worked the ground for 16 years," he added.