Joachim Löw’s side have made a stuttering start to their Group D campaign, losing to Poland in Warsaw and then conceding a late equaliser in the 1-1 draw against the Irish on Tuesday.
It has left them in third spot with just four points – the same total as Scotland, the only team they have beaten in the group.
With the Germans’ failures blowing the group wide open, O’Dea believes Scotland and Ireland – who meet at Celtic Park next month – can realistically finishing ahead of Löw’s side.
The former Celtic player said: “Everything is up for grabs, anyone could top [the group] at this stage. The frightening thing was that Germany were so average on Tuesday. To think they were world champions three months previously – they just offered nothing.
“When you have such a massive achievement like winning the World Cup there might be a bit of a hangover from that. They lost a couple of influential players and, watching them on Tuesday night, something is very amiss.
“From an Irish point of view, you were never worried. It was so comfortable and there was no spark from Germany.
“Next month, Scotland- Ireland will be a massive game. The matches involving Scotland, Ireland and Poland looked like they would be a little mini-league. But even Germany are in there fighting now.”
O’Dea, currently without a club since leaving Ukrainian club Metalurh Donetsk, insists Scotland’s resurgence has come as no surprise after working under “big thinker” Gordon Strachan for three years while on the books of Celtic. He has lauded Strachan’s passing philosophy and has warned his compatriots that they will be coming up against the ultimate football anorak in Glasgow on 14 November.
With three points separating the nations, O’Dea continued: “Gordon is a big thinker. There is a theory for everything that happens on the pitch. Nothing is an accident. He loves football and you will find him watching football in every league around the world. I believe he has a special satellite dish so he can get games from anywhere! No stone will be left unturned for the Ireland match.
“I played under Gordon Strachan at Celtic and I know that every player on the pitch – whether it’s a goalkeeper, centre-half or a centre-forward – is expected to know what to do with the ball.
“That goes a long way towards controlling the game and being strong towards the end of the game, when you will have more legs and energy. Everything Scotland have been doing in the last 18 months has been a big improvement.
“Ireland have a good squad of players and it will be interesting to see how the game unfolds.”
Over 10,000 Irish fans have applied for tickets for next month’s match at Celtic Park.
The SFA offered the Football Association of Ireland just 3,000 tickets in a bid to hand Scotland a home crowd advantage.
A spokesman for the FAI said: “The ticket portal closed around six weeks ago and we had over 10,000 subscriptions.
“We only have an allocation of 5 per cent of the stadium.”
The SFA put the tickets on public sale for both the Ireland game and the friendly with England this week.