Nagelsmann, whose sacking in March 2023 led to Tuchel's arrival, was tipped to return to Bayern, but has now extended his contract with Germany until 2026
After several missed chances in the first half, Brazil's Miranda finally broke the deadlock by tapping in a rebounded shot past goalkeeper Igor Akinfeev in the 53rd minute.
Philippe Coutinho doubled Brazil's lead with a penalty kick less than 10 minutes later. The playmaker's Barcelona team mate Paulinho quickly added another in the 66th minute, expertly heading a flawless cross by Willian into the back of the net.
Russia take on France next week, while Brazil face Germany for the first time since their humiliating 7-1 loss to the European side on home soil in the 2014 World Cup semi-final.