Pep Guardiola has demanded leaders Bayern Munich improve despite picking up their first win of 2015 to stay eight points clear in the Bundesliga with a 2-0 win at Stuttgart.

Huub Stevens' Stuttgart dropped to the bottom of the league following their home defeat while Guardiola's defending champions stayed on course for a third straight title.

Arjen Robben scored his second goal in as many games when he fired home from 13 metres out just before the half-time break.

Left-back David Alaba, who has only just returned from the knee injury he suffered in November, then drilled home a superb free kick from 30 metres to make it 2-0 with 50 minutes gone.

It was Bayern's first win in three matches having been thrashed 4-1 at Wolfsburg and then held to a 1-1 draw at home to Schalke 04 on Tuesday.

"The quality of Arjen Robben and David Alaba made the difference," said Guardiola as his side maintained their huge lead over second-placed Wolfsburg.

"Our game isn't at it's best, especially against a team who were aggressive and had man-on-man marking.

"The result was the most important thing, but we have to improve in order to reach our usual level, but I have a lot of trust in this team. They ran a lot and fought hard."

With only one team in this season's German title race, Guardiola said his side are struggling to find their rhythm after the January winter break.

Bayern travel to Lviv, Ukraine, to face Shakhtar Donetsk in the last 16 of the Champions League in a fortnight and Guardiola says the strain of staying top is showing.

"We still need a bit of time. Perhaps the winter break wasn't so good for us," said the Spaniard.

"You can't play for 11 months at this level and always win.

"It's about running less and playing more, passing the ball as quickly as possible.

"We have to find our game, that is our goal for our next match."

Stuttgart boss Stevens said his team must not let their heads drop in the battle to avoid relegation.

"We mustn't let our heads go down, that is the most important thing at this stage," said Stevens, who took charge in November after Armin Veh was sacked.

"Last week we were 16th, this week we're last, the most important thing is where we are after 34 games."