- Michael Ballack tells CNN the dominance of Dortmund and Bayern is bad for Germany
- Two sides contested Champions League final and are streets ahead in Bundesliga
- The 36-year-old says new Bayern coach Pep Guardiola has a tough job to improve the team
- Ballack played a farewell match in Leipzig as his 17-year career officially came to an end
As Michael Ballack finally calls time on his 17-year professional career, German football can bask in the knowledge they boast the best two teams in Europe.
But while the Champions League final between eventual winners Bayern Munich and Borussia Dortmund showcased all that is good about German football, the 36-year-old has told CNN the domestic game may suffer as a result.
As well as the continent's most glittering club prize, Bayern won the German Cup and the Bundesliga by an incredible 25 points.
Dortmund, who won the championship in the previous two seasons, were their nearest challengers, and the pair have accounted for five of the last six titles.
Ballack told CNN World Sport that duopoly could be bad news for the Bundesliga, if Germany's top league starts to resemble Spain, where Barcelona and Real Madrid reign supreme.
"In Germany we have a situation now where Dortmund and Bayern are far, far more away from the other teams, and that's what we don't want to see in the Bundesliga," said Ballack, who has 98 Germany caps to his name.
"We have a little bit of a similar situation in Spain with Barca and Madrid, and in the (English) Premier League it's more open.
"These last years we could see a lot of surprises, and from the bottom (a team) could beat the first one. It was exciting and the Bundesliga was good to see. Bayern Munich is heading away a little bit so we will see how it develops in the future."
Bayern's historic treble confirmed them as the dominant force in Germany, and with their considerable financial muscle, they are already planning on extending their superiority over the rest.
Shortly before the end of the season it was announced that Mario Gotze -- one of Dortmund's best players -- would be joining Bayern for $49 million, with striker Robert Lewandowski expected to make a similar move in the coming weeks.
While the man who masterminded Bayern's success in 2013, Jupp Heynckes, is retiring, his replacement is Pep Guardiola, who won a total of 14 trophies in four years as coach of Barcelona.
So how can the other teams, Dortmund included, keep up with the Bayern juggernaut?
"With money," Ballack jokes. "No, it's difficult for the weaker teams to close the gap because like I said, the bigger teams still invest, and they could invest.
"If you take Bayern Munich, they just bought six months ago Javi Martinez for $52 million, now Gotze for $49 million. So that's a lot of money and it's not possible I think to do it for any other club in Germany.
"It is just Bayern Munich who has this good position, and from a financial point really good, and really healthy. And that's important.
"Dortmund as well, they are trying to close the gap between them and the other teams, but of course Bayern Munich are far away from the others."
Guardiola comes with a reputation as one of the game's leading coaches, but given the standards Bayern set this season, Ballack thinks the Spaniard will struggle to improve the team.
"I think sometimes when you come in (as a new coach) you think 'I have to change something.' But if you see this Bayern Munich team now, I can't really see where he needs to change.
"Obviously he has his own idea of football and how he wants to play. I'm sure he's seen a lot of games, if not all, in the last six months from Bayern Munich, and he knows there's not much to improve.
"It's an incredible level that they've played in the last six months or the last year. And like I said before, the little details. Maybe change something just to change something because you want to play your own style.
"But on the other side, like I said, you can't really change a lot because everything works well. But I'm sure he's a smart guy and a good coach, and he will handle it."
Ballack's farewell match in Leipzig saw a World XI, coached by new Chelsea manager Jose Mourinho, take on a Germany XI, coached by Rudi Voller.
Former teammates Didier Drogba, now at Galatasaray, Ukrainian Andriy Shevchenko, Bayern captain Philipp Lahm and seven-time Formula One world champion Michael Schumacher, among others, took part.
Mourinho managed Ballack at Chelsea and has now returned to London for a second stint after his three-year tenure at Real Madrid ended in disappointment.
One of the Portuguese's first engagements will be to renew his rivalry with Guardiola when Chelsea play Bayern in the UEFA Super Cup at the end of August.
And Ballack, who won one Premier League title and two FA Cups in his four years at Chelsea, and three Bundesliga crowns with Bayern, says his time with Mourinho was a golden spell in his career.
"He has a fantastic reputation at (Chelsea), also I think in England. He's a charismatic manager and I really enjoyed working with him for two years and most of the players as well I can say.
"I think (his image) is not always what you see in the media. What we have as players, is another picture. And that's the picture in the dressing room.
"It's the daily work with him on the pitch and his speeches when he talks to us. And that's what I can say is special, because his attitude, his personality, if he comes in front of the group if he talks to us.
"What's fantastic is he brought the team behind him. And that shows not just in Chelsea, he also adapted really well on the international (stage). He worked in Italy, he worked in Spain, and everywhere he had success."