Northern Ireland manager Michael O'Neill has warned his players that they cannot afford to underestimate San Marino in Friday evening's qualifier in Serravalle.

The European minnows are ranked at 203 in the world - 180 places behind Norn Iron - and have picked up just two points from 62 previous World Cup qualifiers.

Despite his side being strongly backed to cruise to a comfortable victory on the road to Russia 2018, O'Neill has stressed that Ireland will approach the game as if they were taking on Group C leaders and reigning world champions Germany.

"We've looked at how teams have not played as smartly as they could have and maybe underestimated San Marino," he told reporters. "That's something we've hammered home to the players. The one thing you always want to avoid is complacency in this type of game and the way to do that is to point out the mistakes you've made, your potential weaknesses and to make sure on the night we play as if we're playing Germany or the Czech Republic.

"Having seen the players this week, that's what we anticipate for the type of performance we'll get. We don't envisage it will be easy for us. Whether you win 1-0 or 6-0, it's irrelevant. The key is making sure we win the game. We've had many discussions of where we are as a team in terms of how we would negotiate this group.

"It wasn't easy, particularly when Germany and the Czechs were group winners for the Euros, Norway were beaten in the play-offs and we knew Azerbaijan would present difficulties, as San Marino are capable of as well. The key was could we maintain the momentum after the Euros? And we did that very well in the opening four games.

"I felt once we negotiated the opening four games we were going to be in a good place, which we were. Then you get big results. There's no doubt that the Stuart Dallas goal in Azerbaijan was a huge result for us because Norway and the Czech Republic drew, and it gave us the four-point cushion that we have now. The way the fixtures have fallen, we're in a position to really benefit from that result."

Northern Ireland sit second in Group C and can secure a likely playoff berth with wins over San Marino and Czech Republic over the next three days.