Germany qualified for the 2022 World Cup by crushing North Macedonia 4-0 away to secure top spot in Group J with two games to spare.
A second-half double by Timo Werner and one goal each from Kai Havertz and Jamal Musiala secured Germany's fifth win in their fifth game under new coach Hansi Flick and lifted them to 21 points, with Romania in second place on 13.
All group winners in European qualification automatically secure a place at the tournament in Qatar.
The Germans, who were eliminated in the first round of the 2018 World Cup and the last 16 at this year's Euros, had an early chance with a Thomas Mueller header.
But, as in their 2-1 home win over Romania on Friday, the Germans lacked precision with their final pass and finishing, creating only a handful of chances in the first half until Werner hit the post with a low drive in stoppage time.
Germany, beaten 2-1 by North Macedonia in Duisburg in March, broke the deadlock in the 50th minute when Serge Gnabry split the defence with a superb through ball for Mueller and he laid it off for Havertz to tap in.
Werner then scored twice in three minutes, first drilling in from another Mueller assist in the 70th minute and then curling a shot home from 20 yards out three minutes later.
Substitute Musiala completed the victory seven minutes before the end with his first international goal.