MDC chief negotiator Tendai Biti, asked by reporters when talks would be concluded, said: "If you pray hard, tomorrow. History is being made and mountains are being moved."
A second day of negotiations ended on Wednesday without a breakthrough but will resume on Thursday at 0930 GMT (10:30 a.m. British time), Tsvangirai said.
"The proceedings have been going…they have not concluded. We are continuing tomorrow, because there are some matters still outstanding," he told reporters as he left the talks venue.
Tsvangirai threatened to pull out of the agreement on Sunday after Mugabe allocated key ministries, including defence, home affairs — which oversees the police — and finance, to his ZANU-PF party.
A new government will have to tackle the world’s highest inflation rate of 231 million percent and severe food, fuel and foreign currency shortages.
Mugabe’s party was stripped of a majority for the first time since independence from Britain in 1980 after a March 29 election which the opposition says he rigged to retain power.