Venezuela's opposition leader Juan Guaido took his place in the parliament speaker's seat on Tuesday after a stand-off with the armed forces who initially prevented him from entering Congress.
While Guaido was barred from entering the building by the National Guard for around half an hour, his rival claimant to the speaker position, Luis Parra, occupied the chair.
By the time Guaido was allowed in, alongside allied deputies, Parra had already left.
Lawmakers sang the national anthem but electricity to the chamber was cut off, leaving deputies to use the torches on their mobile phones to provide light.
Earlier, dozens of National Guard troops wearing helmets and carrying riot shields blocked Guaido from entering the building.
"These are not barracks!" shouted Guaido at troops, who had set up a check-point at the building's entrance before the opposition leader arrived.
Inside, Parra, an opposition legislator accused of corruption, was already installed in the seat Guaido has occupied for the last year.
Parra caused a storm on Sunday when he declared himself parliament speaker after the armed forces had prevented Guaido from entering the building.
A year ago, Guaido used his position as speaker to declare himself acting president in a direct challenge to the authority of socialist leader Nicolas Maduro.
He claimed on Sunday to have been re-elected to his post after holding a legislative session alongside loyal deputies at the offices of an opposition-leaning newspaper.
In the parliament building, Parra sat in the speaker's seat while burly men appeared to stand guard at the steps leading up to his seat.
Parra was kicked out of his opposition party last month after an online news site accused him of corruption linked to the over-pricing of food imported for the Maduro regime.
But he remains a deputy and Maduro recognized Parra's election in a television address on Sunday.
The move was denounced by many countries, including the United States and even Maduro's left-wing allies Argentina and Uruguay.
Guaido vowed on Monday to hold Tuesday's parliamentary session and branded Parra "an accomplice to dictatorship."
Parra said Guaido would have the right to attend his session, but as just "another deputy."
Both men claimed on Sunday they had the support of enough deputies to be elected president of the legislature.
Parra's support mainly comes from deputies loyal to Maduro while the opposition holds 112 of the 167 seats in the assembly.
Guaido said 100 deputies voted for him, Parra claimed the support of 81 lawmakers.
The National Assembly is the only branch of government in opposition hands.