The Movement for Democratic Change (MDC) turns 14 this weekend, just weeks after Zanu-PF turned 50.
There are 36 years between them, but both parties are facing similar internal questions about reform.
After its controversial election win, the mood is a little lighter within Zanu-PF than in the MDC, but both parties stand at a critical time in their history.
Both President Mugabe and his bitter rival Morgan Tsvangirai are under pressure to reform their parties and ensure their survival.
Zanu-PF was formed on August 9 1963 at the home of the late Enos Nkala in Highfield after a rebellion against Joshua Nkomo's leadership of Zanu.
Three years earlier, a fiery speech by Mugabe, then an unknown teacher on a holiday break from Ghana, had convinced nationalists to recruit him.
Fifteen years later, Mugabe was leader of Zanu. He has not let go since.
Life after Mugabe
Although he has led his party to victory, his refusal to reform his party – as shown again by his choice of Cabinet this week – raises questions about whether his party can survive for long with or without him.
That a key landmark as 50 years passed without anybody from Zanu-PF noticing is a reminder of how different the party is from the one formed by the nationalists that day in 1963.
Few founding fathers remain, and Mugabe sits peerless within his politburo.
But how long can a leader remain before he starts damaging his party?
"That is the question for Mugabe, but it is a question Tsvangirai is facing too. Can their parties survive them? Can they outlive them even?" asks political scientist Farai Pasirayi.
It is a question Mugabe has faced for years, but it is new for Tsvangirai, who is now into his third term as MDC leader. He has vowed not to step down and has said he will stand for a fourth term in 2016.
Still hanging on
Just weeks before he died this year, Nkala told a reporter: "I have hinted strongly to Mugabe that he has made a mistake by staying in power for too long. I told him that he would lose his reputation because issues cannot remain the same, they continue to change and he must change."
But Mugabe has hung on, and done so for so long that nobody agrees on his legacy.
Will the same happen to Tsvangirai? His former ally and a key fundraiser for the MDC for years, Roy Bennett, appears to think so.
Bennett says the party he joined had changed, and leaders "should do the honourable thing and tender their resignations".
Political analyst Eldred Masunungure said the MDC was losing key domestic and foreign friends, with even some within the party doubting the party would have been able to lead had it won.
"They are saying if the party can't act right, what would have happened when it came to policies if they had captured state power. They need to quickly get their act together, otherwise they risk becoming irrelevant," Masunungure says.
The struggle is 'just starting'
But the MDC insists it is not finished. "Nothing could be further from the truth. The struggle has not ended. It is just starting," says MDC chairperson Lovemore Moyo.
Bizarrely, the MDC's anniversary will run under the theme "Claiming and Celebrating the People's Victory".
Born out of a motley mix of students, workers, wealthy white farmers, big business and a range of activists, the MDC was always going to struggle with identity.
Munyaradzi Gwisai, an academic and founding member of the party, was expelled for calling for a more left-leaning slant.
He said the MDC would die if it does not respond to Mugabe's nationalist rhetoric.
"Without the necessary ideological, strategic and leadership overhaul, MDC cannot counter this, and will suffer gradual terminal decline," Gwisai said.
Same script, different cast
But Mugabe also has to deal with the same division Tsvangirai is dealing with.
The difference is that, where the MDC's divisions threaten Tsvangirai himself, Mugabe is happily using them to his advantage.
He has convinced his party that only he can lead it.
Zanu-PF, unlike the MDC, is able to keep its own divisions under wraps.
This week, one of the reported protagonists of the succession drama, Emmerson Mnangagwa, completely denied there are any such divisions. They were a media creation, he said.
"I read that through newspapers. No one has said that there are divisions in Zanu-PF. I have never said that. The press creates such statements and believes them. We are so united in Zanu-PF. People share different views in the party and it's healthy for the party," Mnangagwa said.
For 50 years, Zanu-PF has survived on a steady diet of intimidation, grass-roots mobilisation and shrewd leadership.
As one senior official said to the Mail & Guardian last week: "We know what gets us ahead."