From being compared to her 'elder sister' in every which way to winning an election as a legislator to awaiting the Supreme Court's verdict, the AIADMK leader has several challenges awaiting her.
T E Narasimhan reports from Chennai.
For 61-year-old V K Sasikala, the past few days have been filled with discussion on taking charge as chief minister of Tamil Nadu.
Tougher times are ahead. She has to win a by-election to the legislative assembly, get cleared in a Supreme Court case and manage a drought-hit and financially struggling state.
Poes Garden, the late J Jayalalithaa's residence where Sasikala and her aides also reside, has been the epicentre of the political discussions on the major change.
Following Jayalalithaa's demise on the night of December 5, the party was left without an uncontested leader and O Panneerselvam, who twice substituted her as CM when she had been legally disqualified from the office, was the choice.
However, the prospects of Sasikala taking over was always there.
It became stronger from party leaders such as Lok Sabha Deputy Speaker M Thambidurai after she took over as head of the ruling All India Anna Dravida Munnetra Kazhagam at the end of December.
Panneerselvam was, meanwhile, gaining acceptance as CM as he made his presence visible on every issue, including the jallikattu protest and turmoil the state has faced.
However, Thambidurai and senior ministers in his cabinet openly said Sasikala should also become the CM.
With the party announcing the MLAs meet on Sunday, along with the change in the top advisors appointed by Jayalalithaa in the CM's office on Friday, the coming change in the government was clear.
Where Pannerselvam stood was not.
He had gone to north Chennai on Sunday morning to take stock of the cleaning of the big oil spill at Ennore port.
Sources say he was called from there to Poes Garden, where seniors finalised discussion with him for the changeover.
People who did not accept Sasikala and her family in the party have alleged that Panneerselvam did not initially agree with the plan.
Reportedly, he wanted the current team to continue.
While he could not be reached for comment, Sasikala in her speech on Sunday after being acclaimed head of the legislature party, said it was Panneerselvam who insisted on her taking charge of first the party and then the CM's office.
During the two-hour meeting ahead of convening the MLAs, it was said that he was offered the job of deputy CM in the Sasikala cabinet. That remains to be confirmed.
The leaders, including he, moved to the AIADMK headquarters, where the meeting of the 134 MLAs took place.
Panneerselvam said he was resigning and Sasikala would take over.
She arrived in the car used by Jayalalithaa and made a short speech.
Grassroots party cadres do not seem so enthused, going by the lukewarm celebrations.
Social media was full of criticism against the decision.
A few AIADMK members have said those who did not like Sasikala to take over as CM did not raise any issue because they did not want to split the party.
The present state assembly was elected less than a year before, for five years.
For the same reason, they say, Panneerselvam is unlikely to join any other party at this juncture.
Also, they note, his son's name has come up in some questionable land deals.
With state Governor Ch Vidyasagar Rao accepting the Panneerselvam's resignation on Monday, Sasikala is expected to be sworn in this week.
The challenges for her are immense.
She will be compared with Jayalalithaa in every action.
Party cadres are unlikely to readily accept her in place of the late leader.
She has to win an election as a legislator.
The Supreme Court has to issue its verdict in the disproportionate assets case, where Jayalalithaa was the first accused, followed by Sasikala and two others.
The order is expected this week.
Local body elections are also expected in the next few months and winning it would be important for her.
The party had a sweeping victory in 2011, when Jayalalithaa was leading it.
The state is also facing one of the worst droughts it has seen in the recent past.
The government's approach on water sharing pacts with neighbouring states would be another test of her strength, said a politician.
The financial situation is also a matter of concern.
Growth rates have dipped and the state has an estimated revenue deficit of Rs 15,854 crore (Rs 158.54 billion) in this financial year, as against Rs 9,481 crore (Rs 94.81 billion) in 2015-2016.
This is apart from the election promises of various schemes pending for implementation.
