A reminder from BBC correspondents that Mr Mnangagwa - who has been made leader of the Zanu-PF party - and the Zimbabwe military are the very people who helped Mr Mugabe hang on to power for so long.
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State TV is broadcasting its evening news but so far hasn't broadcast any special announcement about the future of President Robert Mugabe. It covered today's ruling party meeting at which Mr Mugabe was removed as party leader.
An announcement is however "coming soon", the broadcaster has said on its social media accounts.
Bloomberg says that Mr Mugabe's reported decision to resign came after he was told he would be impeached if he remained president.
Emmerson Mnangagwa has long wanted to succeed Robert Mugabe as president.
After Mr Mugabe dismissed him and publicly accused him of "treachery", his supporters in the security forces where he made his name intervened on his behalf.
Those who fought in the 1970s war, like Mr Mnangagwa, have long monopolised power in Zimbabwe.
Afraid that they would lose their positions if Grace Mugabe were to succeed her husband, as seemed to be on the cards, they took action.
Who is Emmerson Mnangagwa?
- Known as "the crocodile" - his Zanu-PF faction is "Lacoste"
- Received military training in China and Egypt
- Tortured by Rhodesian forces after his "crocodile gang" staged attacks
- Helped direct Zimbabwe's 1970s war of independence
- Became the country's spymaster during the 1980s civil conflict, in which thousands of civilians were killed
- Seen as key link between army, intelligence agencies and Zanu-PF party
- Accused of masterminding attacks on opposition supporters after 2008 election
Zimbabweans are using the hashtag #apolojersey to poke fun at the jumper Zanu-PF youth wing leader Kudzai Chipanga wore when he made a grovelling apology on state-run TV last Wednesday following the military takeover.
The apology, which you can watch below, came a day after he had warned the army chief Gen Constantino Chiwenga to remain in barracks:
Now memes are being shared showing President Robert Mugabe, who has just been sacked as leader of the ruling Zanu-PF party, and his wife Grace, who has been expelled from the party, wearing the same jersey:
- Copyright: AFP/Getty
This photograph shows a Zanu-PF party delegate reacting to the news of Mr Mugabe's sacking as party leader.
The party is heading for a new era under the leadership of the "Team Lacoste" faction, headed by the "crocodile" - the nickname for Emmerson Mnangagwa, the former vice-president who was sacked by Mr Mugabe just two weeks ago.
Some people haven't waited for Mr Mugabe to step down. Footage shot on Saturday shows people destroying a billboard depicting the president in front of the Zanu-PF party HQ.
As Zimbabweans wait for President Robert Mugabe to speak, a BBC correspondent in the capital, Harare, tweets:
President Robert Mugabe has agreed to resign as Zimbabwe's president, the Reuters news agency is quoting a source familiar with the negotiations as saying.
The source said the military, whose commanders met the 93-year-old leader today after he was removed as the ruling party's leader, was working on a resignation statement.
Another journalist in the capital, Harare, is also tweeting that the president will resign, but there has been no official confirmation of this.
President Mugabe is due to give an address on state-run television later today.
BBC News website Africa editor
The key to understanding Mr Mugabe is the 1970s guerrilla war where he made his name.
At the time, he was seen as a revolutionary hero, fighting white minority rule for the freedom of his people - this is why many African leaders remain reluctant to criticise him.
Since Zimbabwe's independence, most of the world has moved on - but his outlook remains the same.
- Copyright: AFP/Getty
- 1924: Born in Zvimba district. Later trained as a teacher
- 1964: Imprisoned by Rhodesian government
- 1980: Wins post-independence elections
- 1996: Marries Grace Marufu
- 2000: Loses referendum, pro-Mugabe militias invade white-owned farms and attack opposition supporters
- 2008: Comes second in first round of elections to Morgan Tsvangirai, who pulls out of run-off amid attacks on his supporters
- 2009: Amid economic collapse, swears in Tsvangirai as prime minister, who serves in uneasy national unity government for four years
- 2017: Sacks long-time ally, Vice-President Emmerson Mnangagwa, paving way for wife to succeed him. Military then takes over. Is himself then sacked as leader of ruling Zanu-PF party
- Copyright: BBC
Broadcaster ZBC has a message on screen telling viewers to stay tuned for Mr Mugabe's address to the nation.
Mr Mugabe has been meeting senior members of the Zimbabwean military and police at State House, reports say.
Pictures from the meeting show him shaking hands with army generals.Copyright: ReutersCopyright: ReutersCopyright: Reuters
There was jubilation at the Zanu-PF party headquarters as Mr Mugabe was sacked as party leader.
Footage shows people singing and celebrating.
Earlier today Zimbabwe's ruling party sacked Robert Mugabe as its leader.
Zanu-PF appointed ex-Vice-President Emmerson Mnangagwa, who was fired by Mr Mugabe two weeks ago, in his place.
The party has given Mr Mugabe, 93, until 10:00 GMT on Monday to resign as president, or face impeachment.
The military intervened last week, in an apparent attempt to block him from installing his wife as his successor.
The first lady, Grace Mugabe, and several other senior officials have been expelled from the party altogether.
Zimbabwe's state broadcaster says President Robert Mugabe will address the nation shortly. He has been meeting the country's military chiefs, who have called on him to step down.