Niko Kovac conceded his Bayern Munich stars struggled to come down from the euphoria of their midweek demolition of Tottenham after suffering their first defeat of the season on Saturday.

Bayern crashed to a first home loss in the Bundesliga for almost a year with a 2-1 defeat by Hoffenheim, just four days after thrashing Tottenham 7-2 in the Champions League.

Bayern kept first place in the table only on goal difference ahead of RB Leipzig, Freiburg, Schalke and Bayer Leverkusen, with the top five teams all on 14 points.

However Borussia Moenchengladbach, who are sixth, can usurp Bayern and finish the weekend top if they beat Augsburg at home on Sunday.

"Yes, it probably was," Kovac admitted when asked if the defeat was down to Bayern's mentality.

"The head controls a lot. We needed to be more energetic, especially in the first half.

"We should have played better, I expected more determination.

"We didn't give as good an account of ourselves as we did in London, now we have to digest and process this defeat.

"We have two weeks now (during the international break) and hope everyone comes back healthy."

Second-half efforts by striker Sargis Adamyan sealed a first-ever win at Bayern for Hoffenheim, with Robert Lewandowski's 11th goal of the season not enough for the hosts.

The Poland star has scored in each of the first seven league games this season and struck 15 times in all competitions.

However the match belonged to Armenia international Adamyan, who was playing regional football two years ago and cost Hoffenheim just 1.5 million euros ($1.6 million) from Jahn Regensberg in May.

He swept home early in the second half after ex-Bayern midfielder Sebastian Rudy robbed possession off Corentin Tolisso.

"Of course, that shouldn't have happened," Kovac said.

"You have to play the ball back to Manuel (Neuer) or Niklas (Suele), then nothing can happen if you have a man at your back."

After Lewandowski's equaliser, Adamyan got the better of Bayern defender Jerome Boateng for the winning goal 11 minutes from time, threading the ball through the centre-back's legs.

"We gave the ball away easily twice and that led to two goals against us," said Kovac.

"If you make two mistakes, they will be punished in the Bundesliga."