By Marina Denysenko
BBC News, Ukraine
Orange-clad protesters call her "Goddess of the Revolution" while outgoing President Leonid Kuchma and some of the oligarchs - Ukraine's business and political elite - are believed to hate her.
Lady Yu has already hinted she wants to be next prime minister
Glamorous Yulia Tymoshenko, one of the key figures of the ongoing Orange Revolution in Ukraine, ignites passion on both sides.
She is a close ally of Viktor Yushchenko, the leader of the Ukrainian opposition that believes he won the bitterly disputed presidential run-off on 21 November.
Recent events have elevated Ms Tymoshenko's popularity to new heights, literally. On one occasion, riot police guarding Mr Kuchma's office raised their shields to allow her through to where talks were being held.
On another, she perched on top of a bus, from where she whipped the crowd into a frenzy with her calls for the government's resignation.
"I would even prefer her to be the president," one of the Kiev protesters says.
In her speeches, Ms Tymoshenko has referred to Mr Kuchma as a "red-haired cockroach".
And when talking about the supporters of Viktor Yanukovych, who claimed victory in the election, she suggested they should hang themselves on the blue and white scarves they wear.
Yushchenko and Tymoshenko are symbols of the Orange Revolution
Her opponents say she is demagogic and pretentious.
She sports an elaborate hairdo reminiscent of a peasant plait, meant to appeal to ordinary Ukrainians.
But her followers point to her intelligence and charisma.
Ms Tymoshenko is seen as one of the candidates for the post of prime minister in post-Kuchma Ukraine, and that makes many Ukrainians feel uncomfortable.
They point to her controversial past when in the 1990s she reportedly made a fortune from questionable gas trading.
She was briefly arrested in February 2001, but the next month a court in Kiev quashed all the charges and annulled the arrest warrant.
She became one of the key players in Mr Yushchenko's government of 1999-2001, launching an all-out assault on the oligarchs' interests in Ukraine's highly corrupt energy sector.
As the result of her efforts, some $2bn were re-directed into the state budget.
Ms Tymoshenko's critics say that once she is in power she is likely to be driven by revenge for those oligarchs in the energy sector.
Lady Yu's charisma
Her radicalism is offset by the more moderate tactics of Mr Yushchenko.
"If Tymoshenko had been in charge, the breakthrough would have already been achieved," BBC Kiev office head Svitlana Dorosh says.
But local observers agree that Mr Yushchenko's team needs such a personality. With a new poll just days away, it is essential
to keep the momentum of the street protests going, they say.
And the charisma of Lady Yu may be indispensable.
Mr Yushchenko's flamboyant aide is adored by the crowds that seem to have forgotten that she used to be an oligarch herself.