Finance Minister Heng Swee Keat, who suffered a stroke in May, will resume his duties, after doctors gave him the green light to do office work, but with minimal interaction with people.
National Development Minister Lawrence Wong will be made second minister to help run the Finance Ministry, said Prime Minister Lee Hsien Loong.
He announced this after resuming his National Day Rally speech at 10.40pm yesterday. He had taken ill while speaking and the Rally was suspended for more than an hour.
When he came back on stage, Mr Lee stressed the importance of leadership succession. "What happened makes it even more important that I talk about it now."
Building leadership and preparing for succession are his top priorities: "Nothing that has happened has changed my timetable, or my resolve to press on with succession."
Mr Lee said he will reinforce his team again at the next General Election. "Soon after the next GE, my successor must be ready to take over from me. Sui yue bu liu ren (Time does not stand still for man). You cannot wait." While the core team for the next-generation Cabinet is in place, ministers are also mortal, he said.
"Heng Swee Keat recently gave us a bad scare - worse than what I gave you just now, much worse," he said. "I am very glad he pulled through."
Mr Heng, a key member of the fourth-generation leadership, had collapsed from a stroke on May 12. He was taken to Tan Tock Seng Hospital where surgery sealed off an aneurysm in his brain.
He was discharged from hospital six weeks later and a video showed a slimmer Mr Heng thanking the medical staff who cared for him .
"It is a miracle that he is all right," Mr Lee said, as he lauded the Singapore Civil Defence Force (SCDF) team that responded to the emergency for "an excellent job".
The same team of paramedics, who were guests at the rally, helped treat Mr Lee last night.
Doctors have recommended Mr Heng avoid crowds for a few more months to minimise the risk of infection, Mr Lee said. While this rules out community and grassroots work, doctors say he can go to work.
Deputy Prime Minister Tharman Shanmugaratnam will then stop covering his duties as Acting Finance Minister.
In a Facebook post last night, Mr Heng said he will focus on next year's national Budget and the Committee on the Future Economy, which he co-chairs with Minister for Trade and Industry (Industry) S. Iswaran. He also welcomed Mr Wong's appointment, saying they had worked closely at the Education Ministry when Mr Wong led the Committee on University Education Pathways beyond 2015.
PM Lee said it was critical to have good people who are capable, committed and have integrity in politics, in order for the political system to continue working properly.
He made the point in the speech he was scheduled to give but did not deliver after he took ill. His office gave the media the speech.
Mr Lee also said he wanted to bolster his team from all fields, including academia and civil society, but it was difficult to convince good people to enter politics.
The suitable few are very difficult to persuade, he said. "I hope you feel strongly enough for Singapore that if we ask you, you will say 'yes'."