Hansi Flick is concerned Bayern Munich are currently too reliant on Manuel Neuer as the European champions prepare to defend their slim Bundesliga lead at Stuttgart on Saturday.
Having produced two reflex saves in last weekend's 1-1 draw with Werder Bremen, Neuer was again superb on Wednesday in a 3-1 home win against Salzburg which secured them a spot in the Champions League last 16.
"It's sensational how he parries big chances and saves us from conceding goals. He had a few things to do -- too much for me," said Flick.
The 34-year-old Neuer brushed off the praise after making 10 saves against Salzburg, saying that "the most important thing is to support the team".
Yet his form has landed Neuer on the FIFA short-list for best male goalkeepers.
"He's in the shape of his life," added Flick, whose team qualified for the Champions League knockouts as guaranteed group winners on Wednesday after their 15th straight win in Europe.
"When opposing forwards approach him, the goal gets smaller and smaller for them. He has amazing reflexes. We have a world-class goalkeeper between the posts."
However, Bayern are guilty of giving possession away too cheaply, like when a Leroy Sane mistake resulted in Salzburg's consolation goal.
"There are too many unnecessary ball losses, we have to minimise our mistakes, these are the issues I have always addressed," complained Flick.
It's been 13 years since Bayern lost at Stuttgart, whose top-scorer Nicolas Gonzalez is sidelined by a knee injury.
Bayern striker Robert Lewandowski has scored 11 goals in seven games to make him the league's top-scorer, but Dortmund's Erling Braut Haaland is lurking just one goal behind and in red-hot form.
Second-placed Dortmund host Cologne on Saturday with Haaland having scored six goals in his last two games.
The Norwegian goal ace netted twice against Brugge on Tuesday in the Champions League after hitting four against Hertha Berlin in the league last weekend.
Dortmund have won six of their last seven games and all of their last four games against Cologne.
One to watch: Breel Embolo
The Swiss striker scored with a spectacular bicycle kick as Borussia Moenchengladbach's 4-0 win over Shakhtar Donetsk on Wednesday edged them closer to the last 16 of the Champions League.
Gladbach team-mate has nicknamed Embolo "Captain Tsubasa" after his stunning kick was reminiscent of the Japanese cartoon football star.
"The boys will say that the goal is typical of me: I put away the most difficult ball and missed the easier ones," Embolo quipped.
A point against Inter Milan next Tuesday will put Gladbach in the knock-out phase of the Europe's top competition.
Strugglers Schalke visit Borussia Park on Saturday evening.
It has been a turbulent week for the Royal Blues, who sacked striker Vedad Ibisevic and suspended midfielders Amine Harit and Nabil Bentaleb amid disciplinary issues.
Schalke are winless in their last 24 games, so expect Embolo and Gladbach's attack to inflict more misery.
201 - the clean sheets Neuer has kept in 401 games in all competitions for Bayern Munich since 2011.
33 - the goals Haaland has scored in 31 games for Dortmund since his January transfer from Salzburg, including 17 in 13 matches this season.
71 - the Champions League goals Lewandowski has scored in his career, leaving him joint third on the list of top European goalscorers.
5 - Werder Bremen have drawn all of their last five league games 1-1 and can set a curious league record with the same result at Wolfsburg on Friday.
Fixtures (all times 1430GMT unless stated)
Wolfsburg v Werder Bremen (1930)
Borussia Dortmund v Cologne, RB Leipzig v Arminia Bielefeld, Union Berlin v Eintracht Frankfurt, Augsburg v Freiburg, Stuttgart v Bayern Munich, Borussia Moenchengladbach v Schalke 04 (1730)
Bayer Leverkusen v Hertha Berlin, Mainz v Hoffenheim (1700)