By Karolos Grohmann
BERLIN, Jan 23 (Reuters) - Leaders Bayern Munich must quickly ditch any lingering holiday spirit or risk a bumpy Bundesliga restart at Borussia Moenchengladbach on Friday, midfielder Thomas Mueller warned.
The Bavarians suffered a surprise 3-0 defeat to Austria's Salzburg in a friendly last week and Mueller said the result was proof that the runaway leaders needed to up the tempo against Gladbach.
"Gladbach will make our lives very difficult," Mueller said on Thursday. "We have to snap out of that holiday atmosphere because there are three points up for grabs."
"Saturday's defeat was good in a way because it showed us that with just half of our commitment you cannot achieve anything," said the Germany international.
Bayern stormed into a seven-point Bundesliga lead over second-placed Bayer Leverkusen and a further 11 from third-placed Gladbach before the traditional break in December. Borussia Dortmund are a further point behind in fourth.
They are through to the Champions League Last 16 where they will face English leaders Arsenal as they seek to become the first club to win back-to-back titles. They are also on track to defend the German Cup.
Bayern coach Pep Guardiola will have to deal with some injury problems, though, with Arjen Robben back in training in the last few days following a seven-week absence.
"I am obviously not at 100 percent yet," the 30-year-old Dutchman told reporters on Wednesday.
Holding midfielder Bastian Schweinsteiger is also still nursing an ankle injury and missed training this week, making his participation also doubtful and raising questions about his fitness for the rest of the season.
The Germany international has failed to hit top form this season, plagued by the nagging injury that required surgery last year and saw him miss the start of the season.
Gladbach will be a tough nut to crack, having set a string of club records en route to a third-place finish at the start of the winter break. They have dropped just two points in their nine home games this season.
The five-times German champions will be without defenders Tony Jantschke and Roel Brouwers but will have Spaniard Alvaro Dominguez back after he broke his shoulder in October.
"We are ready for Bayern," said Dominguez, whose were unbeaten in eight games before the winter break.
"We have been training hard and we are third in the league after all. We want to give Bayern in their own stadium a run for their money."
Leverkusen, eager to remain on Bayern's heels and secure second spot, travel to lowly Freiburg on Saturday.
Fellow Champions League competitors Dortmund, still without injured Ilkay Guendogan, Mats Hummels and Neven Subotic, host Augsburg and are in desperate need of a home win after losing their last three league matches at their stadium.
Schalke, the fourth German team to advance in the Champions League, will be hoping striker Klaas-Jan Huntelaar will make his comeback after a five month injury absence when they travel to Hamburg on Sunday. (Reporting by Karolos Grohmann. Editing by Patrick Johnston)