During the trial, the former Marxist guerrilla will defend herself against charges that she fiddled state accounts
Brazil's suspended president Dilma Rousseff enters her final battle to win back power on Thursday, when senators open an impeachment trial expected to remove her from office for good.
That would formally end 13 years of leftist rule in Latin America's biggest economy.
During a trial expected to last several days, the former Marxist guerrilla, 68, will take the stand to defend herself against charges that she fiddled state accounts.
She denounces the impeachment drive as a "coup" by her rivals, led by her replacement, former vice president Michel Temer.
"In the Senate, I will argue not only for democracy and respect for the direct vote of the Brazilian people, but also for justice," Rousseff told reporters on Thursday.
But media estimate that most senators will vote to remove her.
"This will be the last chance she has to defend herself.
For our part, we will treat her with respect," said one of the senators seeking to impeach Rousseff, Cassio Cunha Lima.
"It will also depend on her attitude. If she is aggressive and provocative, there will be a reaction," he told AFP
The trial opens on Thursday, August 25, four days after the Olympic Games closing ceremony in Rio de Janeiro.
Rousseff is scheduled to appear in person to defend herself on August 29.
Senate president Renan Calheiros said the final vote would likely take place on August 30.
If two thirds of the senators vote against her, she will be out.
"Dilma would need a miracle for that not to happen," said political analyst Everaldo Moraes from Brasilia University.
"Even her own allies can see that."
Rousseff survived torture in the 1970s under Brazil's military regime. She later beat cancer and became the country's first woman president.
But she was unable to resist the turning of the political tide as she struggled to cope with a recession that hit in 2014 and failed to maintain alliances.
"She made every kind of mistake that a president can make," said Sergio Praca, an analyst at the Getulio Vargas Foundation.
"She failed to keep her campaign promises, didn't pay enough attention to her coalition, ignored her own party and didn't listen to anyone."
Political chaos and scandal have compounded Brazil's recession.
A probe into corruption in the state oil firm Petrobras has implicated Rousseff's rivals and allies. The impeachment, however, is not linked to the scandal.