In an interview with the BBC, Suu Kyi said her National League for Democracy expects to win 75 per cent of the seats contested in the 664-member two-chamber Parliament.
By afternoon, the Union Election Commission had announced results only for 88 lower house seats, giving 78 to the NLD and five to the ruling party from Sunday's vote. It has given no explanation for the slow results.
"That is the preliminary calculation," he told The Associated Press, without elaborating.
Official results for 33 upper house seats, released this evening, supported the NLD's optimism, 29 went to the opposition party.
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But the delay has raised concern, with NLD spokesman Win Tien telling reporters that the election commission has been "delaying intentionally because maybe they want to play a trick or something."
"It doesn't make sense that they are releasing the results piece by piece. It shouldn't be like that," he told reporters after a party meeting at Suu Kyi's house.
The surprising accusation added a worrying twist to what had been an amicable election, with the ruling party appearing to be taking its expected loss gracefully.
It is also disconcerting because Myanmar's former military junta, which had called elections in 1990 after 28 years in power, refused then to recognize the NLD's overwhelming victory. It continued its brutal rule for two more decades, keeping Suu Kyi under house arrest for much of that period.
Faced with intense international pressure after becoming a Southeast Asian pariah, the junta finally gave up power in a choreographed transition to democracy, being replaced in 2011 by the Union Solidarity Development Party, largely made up of former junta members.
In the BBC interview, Suu Kyi was asked why, given the events of 1990, things will be different this time.
"They've been saying repeatedly they'll respect the will of the people and that they will implement the results of the election," she said.