Burki has impressed Tuchel since the coach replaced Jurgen Klopp in June, and has been installed as Dortmund's goalkeeper for the upcoming Bundesliga campaign.
Weidenfeller - who has won two league titles with Dortmund since arriving in 2002 - will be first choice in Europe, but it appears he can expect to spend a lot of time on the bench domestically.
"Roman Burki will be in goal [against Borussia Monchengladbach on Saturday], this decision applies to the Bundesliga season," said Tuchel. "Roman Weidenfeller will play both games in the Europa League playoffs."
Dortmund hosts Monchengladbach in its opening league clash and Tuchel is confident his side is ready to put last season's disappointments - when it flirted with relegation before finishing seventh - firmly behind.
Tuchel added: "We feel absolutely ready, but we will have to play very carefully.
"We will need our best possible performance to win the match, Gladbach are one of the hardest and most complex opponents."