Germany coach Joachim Low believes Bayern Munich will face a sterner test to claim a fourth successive Bundesliga title this season.
Pep Guardiola's side secured the 2014-15 championship by 10 points from Wolfsburg, and enjoyed winning margins of 19 and 25 points in the previous two campaigns.
The arrivals of Arturo Vidal and Douglas Costa have strengthened Bayern further over the close season, making them firm favourites for the title, however Low believes they will face a tougher challenge in 2015-16.
"With the acquisitions of Vidal and Costa they [Bayern] have become even more flexible," he told the DFB website.
"Pep Guardiola has a squad with almost unprecedented quality, [but] that does not mean that the title has already been awarded.
"The development in Wolfsburg is impressive, I trust Dieter Hecking and his team a lot. Wolfsburg have kept their squad together and added a top player in Max Kruse.
"Other teams have the potential to make the championship more balanced, Wolfsburg are not the only team who can challenge Bayern.
"There are some new pairings which are interesting.
"I like the work of Thomas Tuchel and am very interested to see how quickly absorbed his ideas are at Borussia Dortmund. Similarly this applies to Andre Breitenreiter and Schalke."
