Thomas Mueller netted twice as Germany eased to an impressive 3-0 home win over the Czech Republic to keep them top of their World Cup qualifying group on Saturday.

It leaves Germany with a perfect six points ahead of Tuesday's next qualifier, home to Northern Ireland, who beat San Marino 4-0 in Belfast.

Germany stay top of Group C on goal difference from surprise-package Azerbaijan on the road to Russia 2018.

"We can be very happy with the win and we had a good grip on the game," said Germany coach Joachim Loew. "After 60 minutes you could see the opposition had run themselves into the ground and didn't have any more clear chances."

After Mueller gave Germany an early lead, Toni Kroos weighed in with a crisp strike just after the break.

Mueller then hit Germany's third with the best goal of the game midway through the second half to cap a polished display from the world champions.

"We're very serious about these two games [against the Czech Republic and Northern Ireland], we could have scored more goals, but we delivered a very concentrated performance," said Mueller.

"The fans deserve praise, the atmosphere was really good. It made it even more fun to play for Germany and, of course, I am happy to have scored twice."

With his only out-and-out striker, Mario Gomez, injured, Loew opted to play Mario Goetze as his lone striker, in front of attacking midfielder Mesut Ozil with Julian Draxlerand Mueller on the wings. The Czech Republic dealt Loew the heaviest home defeat of his 10-year tenure when they won 3-0 in Munich in October 2007 in a Euro qualifier.

But with veteran midfielder Tomas Rosicky injured and goalkeeper Petr Cech now retired, Czech shot-stopper Tomas Vaclik had a busy night.

Meanwhile, Kyle Lafferty struck twice, Steven Davis converted a penalty and Jamie Ward also scored to hand Northern Ireland a 4-0 win over San Marino, while Norway suffered a shock 1 -0 loss away to Azerbaijan, who now have two wins from two.

Robert Lewandowski, Mueller's strike partner at Bayern Munich, tormented Denmark as he grabbed a hat-trick in a 3-2 victory in Warsaw to leave Poland level on four points with Montenegro and Romania in Group E.

Romania thrashed 10-man Armenia 5-0 in Yerevan as the visitors punished their opponents after the dismissal of Gor Malakyan in just the third minute, while Montenegro defeated Kazakhstan by the same scoreline.