Myskina said she would stop playing for Russia in the Fed Cup if the 17-year-old Wimbledon champion was invited to join the team next year.
"If she (Sharapova) joins our team next season you won't see me there for sure," said the French Open champion, who is spearheading Russia's challenge for their first Fed Cup title against France this weekend.
"I don't want to be on the same team with people who don't show respect to me as a person. End of story."
Myskina was angry at Sharapova's father Yuri for his behaviour during their match at this month's WTA Tour Championships in Los Angeles. Sharapova beat Myskina in the semi-finals on her way to capturing the season-ending title.
On the surface at least, the feud between Russia's top two players appears to be pure sport -- everyone wants to be number one in their own back yard.
But in Russia the battle for the supremacy in women's tennis is as fierce as one can find in any sport, with four Russians among the top six in the world and three more in the top 15.
But several people close to the Russian team say the divide is actually much deeper than it seems at first glance.
"They (the players) are just jealous of Sharapova," a source within the Russian tennis federation told Reuters. "They resent her sudden fame and fortune."
RUSSIAN HERITAGE
While U.S. Open champion Svetlana Kuznetsova and the rest of Russia's Fed Cup team have publicly distanced themselves from the controversy, privately they all supported Myskina.
"I think this year's team has a great spirit and all the girls are very supportive of each other," said Kuznetsova when asked to comment on the Myskina v Sharapova standoff. "I don't know if we're going to have the same camaraderie in the future."
Sharapova has been kept out of this year's team by Myskina and Kuznetsova, but Russia Fed Cup captain Shamil Tarpishchev said he would welcome the Florida-based
Kuznetsova herself acknowledged her dislike of Sharapova at last month's Kremlin Cup.
When asked who is the most popular Russian player worldwide, the world number five said with a wry grin: "Sharapova of course -- but I don't know if you would call her Russian though."
The Siberian blonde left Russia at the age of seven to train at the famous Nick Bollettieri academy and has rarely been back to her homeland since.
Despite repeatedly pointing to her Russian heritage, Sharapova speaks the mother tongue with a heavy foreign accent and disappoints local fans by choosing not to play in Russia.
Tarpishchev tried to play down the latest controversy, which could jeopardise his team's chances of capturing the Fed Cup crown, but others see it as a case of deja vu for Russia.
"Things like this happen all the time," said the source at the Russian tennis federation. "When you have so many talented girls on the same team and every one of them sees herself as a future star in her own mind, you're bound to have ego clashes."
LEFT COUNTRY
Ever since some Russian players, like Anna Kournikova, left the country at an early age to learn their trade elsewhere, the ones who stayed behind have shown their resentment toward those who quit.
Kournikova was the first Russian in the post-Soviet era to make headway on the WTA Tour when as a 16-year-old she reached the Wimbledon semi-finals in 1997.
But despite her photogenic looks, worldwide appeal and multi-million bank account, the Russian blonde has never been very popular with fans or fellow players back home.
When another long-legged Russian, Elena Dementieva, followed Kournikova on to the international stage, she resisted any comparison.
When asked about her relationship with Kournikova several years ago, Dementieva said: "We hardly see each other. I live in Moscow and she lives in the United States.
"And I've never refused to represent my country," added Dementieva, taking another swipe at Kournikova, who has repeatedly turned down a chance to play for Russia in Fed Cup.