Northern Ireland Michael O'Neill feels "breathtaking" Germany's squad could be even stronger than their World Cup-winning side of 2014 after they booked their passage to Russia with a 3-1 victory in Belfast. Die Mannschaft maintained their astonishing record of having never lost an away World Cup qualifier in their history by inflicting a first competitive home defeat on Northern Ireland since 2013.Cristiano Ronaldo was their tormentor-in-chief that night, but there were multiple scourges at Windsor Park as Sebastian Rudy's delicious 30-yard opener after 83 seconds was added to by Sandro Wagner's emphatic strike and Joshua Kimmich's sweet volley before Josh Magennis' late consolation.Joachim Low had just six World Cup winners available to him in Belfast, though the remaining players apart from Manchester City's Leroy Sane won the Confederations Cup in the summer, and O'Neill was left marvelling at their strength in depth." I'm not sure if there's a system you can come up with that can contain Germany," O'Neill argued. "The quality of their play at times is breathtaking, in terms of how they move the ball and the movement of their players. "We had two League One players and Championship players, they don't play that style, players of that calibre. It's a huge education for our players and it will acquit us well. One thing I'll say about playing Germany, whoever you play after seems a lot easier! "If you look at the starting line-up, their oldest players are 28, 29, it gives you an indication of what's coming in."I would imagine in Russia Germany are going to have a fantastic squad and possibly even a stronger squad than four years ago. It just seems there's a never-ending conveyor belt of talent coming through. They'll be a formidable team to beat in Russia."They ripped up O'Neill's best-laid plans after just 83 seconds when Rudy smashed beyond Michael McGovern to end his 10-hour run without conceding in international football."It's the worst start we could have had," O'Neill admitted."There's very little you could do about it with the quality of the strike so early in the game. We probably had a number of players who hadn't touched the ball."It never gave us a chance to settle, the approach we had was designed to stay in the game as long as possible, you can't go and chase it too early against a team of this quality. It made it difficult for us - the first 15, 20 minutes it really knocked us back."Whether Northern Ireland will be in Russia remains unclear as only an unlikely victory on Thursday would have assured them of a play-off place.It would be confirmed before they face Norway on Sunday if Bosnia and Herzegovina do not beat Belgium and Greece do not beat Cyprus on Saturday.Even then, with the play-offs being seeded, O'Neill would be reluctant to field a weakened XI in Oslo, despite six of his squad being one booking from a suspension."I don't have four players from Bayern Munich on my bench, it's not that easy for me to rotate my squad," O'Neill noted."We want to go out and try and get three points and try and make sure we're not beaten. We can't allow ourselves to field an inexperienced team and be beaten and (maybe) suddenly lose out on goal difference. It is very important."Were they to make the November play-offs and not be seeded, a clash with Portugal or Italy could await Northern Ireland.Low, whose men have faced them three times over the past 16 months, believes they could still join them at the finals were they to draw such a foe."Northern Ireland have a population of just under 2,000,000 and they were absolutely competitive in our group," Low noted."There has been hardly any gap (in the group) between them and us."Of course it will be tremendously difficult to beat a team like Portugal or Italy over two games but they can do it."