The war of words between Malaysian Prime Minister Mahathir Mohamad and the Johor crown prince Tunku Ismail Sultan Ibrahim over the powers of the constitutional monarchy to interfere in political matters hit the headlines last month.
The row escalated this month when Tun Dr Mahathir, 93, called 34-year-old Tunku Ismail "a little boy" and "stupid".
Johor ruler, Sultan Ibrahim Sultan Iskandar and Raja Permaisuri of Johor, Raja Zarith Sofiah Sultan Idris Shah, the mother of Tunku Ismail, also joined in the fray, with the latter leaping to her son's defence.
The Straits Times takes a look at the testy relations between Dr Mahathir and Johor's royal family which date back to the early 1990s.
1. KL's manoeuvres against Johor royals hit home
The Mahathir Mohamad administration appears to have fired a decisive shot across the bow of the Johor royalty this past week, with the palace seemingly making a hasty retreat after alleged land-grab exposes and tax evasion tainted the ruler of the southern state's self-styled image as a caring monarch.
Political insiders told The Straits Times that while only one such attack came directly from the Prime Minister's Office, it was a concerted campaign that could end the escalating feud that has seen the mercury rise for months. It has been a war of attrition that has eroded the standing of both the government and the Johor monarchy among the Malay majority who see the rulers as guardians of their interests.
The heated battle between Prime Minister Mahathir and the Johor royals flared up over the selection of top officials for Johor last month. It came hot on the heels of the Pakatan Harapan (PH) government backing out of plans to sign up to the International Criminal Court early last month following sustained claims, led by Johor's Crown Prince, Tunku Ismail Sultan Ibrahim, that the move would open up the Malaysian King to prosecution for war crimes, genocide and crimes against humanity.
2. Mahathir outnumbered in deja vu battle with Malaysia's royalty
The Frank Sinatra hit My Way has long been associated with Tun Dr Mahathir Mohamad, mostly because the 22 years when he was in charge the first time around was typified by a determination to get things done "his way" to the point of being utterly inflexible.
Yet it was never lonely at the top for the man who ruled supreme from 1981 to 2003 at the head of the once dominant Umno-led coalition, which had a two-thirds super-majority in Parliament.
But just shy of the anniversary of his shock return to the helm, the Grand Old Man of Malaysian politics - who stormed back into Putrajaya at the age of 92 - appears to have finally crossed a bridge too far by going head to head with an old foe - Malaysia's royalty.
3. Mahathir v Johor royals: Bad blood stretches back to 1990s
Prime Minister Mahathir Mohamad's fierce exchanges with the Johor royalty in recent weeks have focused on Kuala Lumpur's now-retracted decision to accede to the International Criminal Court (ICC) and on appointments to the state government.
But the genesis of the bad blood stretches back not just to the Crown Prince's call not to vote for Tun Dr Mahathir in last year's election, but to the early 1990s, during the 93-year-old leader's first period in office when the government removed immunities enjoyed by Malaysia's Malay rulers following episodes of assault by Johorean royalty.
Since Dr Mahathir first retired after 22 years in power in 2003, Malaysia's nine monarchies have flexed increasingly larger muscles, with Sultan Ibrahim Sultan Iskandar's influence in the southern state impacting not just the selection of political leadership, but also business decisions.
4. Mahathir v Johor royals: Don't worry, Mama, says Crown Prince after she defends him
The mother of Crown Prince Tunku Ismail Sultan Ibrahim has leapt to his defence after Malaysian Prime Minister Mahathir Mohamad's fierce exchanges with the Johor royalty in recent weeks.
The Raja Permaisuri of Johor, Raja Zarith Sofiah Sultan Idris Shah, said in a Facebook post, that she could not bear to see Tunku Ismail being showered with criticism from all quarters after his comments that his father, Sultan Ibrahim Sultan Iskandar, has absolute authority to choose the state's Menteri Besar.
"As a mother who had excruciatingly witnessed one of her children drawing his last breath and subsequently laid to rest, then it is not wrong for me to feel distressed to see one of my children being insulted, ridiculed and become an item of entertainment for those who think they are smarter and have never committed any wrongdoing."
5. Test of strength between royal households and Mahathir looms
The unfolding political crisis in Johor triggered by the resignation of the state's Menteri Besar Osman Sapian this week is threatening to turn into a test of strength between Prime Minister Mahathir Mohamad's government and the country's royal households.
Since Datuk Osman resigned on Monday, Tun Dr Mahathir - whose relations with the country's royalty have long been prickly - and the Johor palace have given sharply different opinions on who will get to decide on his replacement.
The public exchange of words is raising the spectre of a fresh and potentially ugly constitutional crisis that could raise the already high political temperatures in Malaysia after last year's divisive general election.