England and Russia are fully aware of the potential pitfalls of facing weaker opposition when they tackle Wales and Armenia respectively on Saturday.
Spain and Italy provided good examples of how to avoid a qualifying slip up on Friday, although it took the two most recent world champions until the 73rd minute to seal valuable wins against the lower ranked Czech Republic and Slovenia.
Fabio Capello's England side travel west to the cauldron of noise that is the Millennium Stadium in Cardiff (1500 GMT) looking for a crucial three points that would pull them level with surprise Group G pacesetters Montenegro.
Russia meet Armenia in Yerevan (1500) knowing their hosts, Slovakia and Ireland are breathing down their necks in Group B.
Germany host Kazakhstan (1900) and should chalk up their fifth win from five qualifying games against a team stuck at the bottom of Group A and who are yet to score.
Scandinavian rivals Norway and Denmark play in Oslo (1900), with the home team looking to preserve a perfect qualifying record that sees them top Group H above Portugal.
The top two in Group F, Croatia and Greece, travel to Georgia and Malta respectively, while in Group D Belarus play in Albania hoping to move back to within a point of leaders France.