An unsatisfied Joachim Low admits Germany "got lucky" to come away with three points after its late 2-1 win over Czech Republic in Prague.

Bayern Munich defender Mats Hummels headed in an 88th-minute winner on Friday to improve the world champion's record to seven successive victories in Group C of qualifying.

But it was far from straightforward as Vladimir Darida cancelled out Timo Werner's early opener with a thumping equaliser 12 minutes from time. 

And despite Hummels' header preserving Germany's five-point lead, head coach Low was left unconvinced by his side's performance as the Czechs regularly threated on the counterattack.

"We definitely cannot be happy with the way we played tonight. We got lucky," the Germany boss said after the match.

"Czech Republic defended well, but we also made things very difficult for ourselves." Hummels' goal was his first for Germany since netting the winner in the 2014 World Cup quarter-final against France.

While pleased with his match-winning impact, the 28-year-old agreed with Low's assessment of the team's display. "The goal obviously felt very good [but] we gave the ball away too easily, too often. That is unlike us," Hummels said.

Germany's next assignment is at home to Norway on Monday, with matches against Northern Ireland and Azerbaijan to follow in October.