"Klinsi-KO: How long will the bosses allow him to keep losing?" was the headline in Bild, Germany's largest circulation daily.
Among Klinsmann's controversial moves since taking the Bayern helm last summer was bringing Donovan in on loan from the Los Angeles Galaxy to boost the Bayern offense. But Donovan failed to help Bayern in five appearances off the bench in which Bayern lost three, tied one, and won once in its league games since the winter break.
Bayer Leverkusen, whose league run since the winter break was just as dismal as Bayern's, opened up a 3-0 lead in the cup game before goals by Lucio and Miroslav Klose made it 3-2 by the 74th minute. But Bayern's comeback attempt fell short and Leverkusen added a fourth by Stefan Kiessling in stoppage time in the game attended by 50,500 in Duesseldorf.
Klinsmann, whose assistant coach is Mexican-American Martin Vasquez, took over a team that won last year's Bundesliga and German Cup titles. Bayern has fallen to fifth place in the league, four points behind leader Hertha Berlin.
The highlight of Bayern's performances since the winter break was an impressive 5-0 win at Sporting Lisbon Feb. 25 that virtually guarantees passage into the quarterfinals of the Champions League. Donovan watched that game from the stands.
On Saturday, Bayern hosts Hannover 96 in the last game before Donovan's return to the Galaxy.
"The most important thing now is to crown the season with one or the other title," Klinsmann told Bild after Bayern's German Cup defense ended.
GERMAN CUP, quarterfinals
Mainz 1 (Bance 88) Schalke 04 0
Bayer Leverkusen 4 (Barnetta 54, Vidal 61, Helmes 70, Kiessling 92) Bayern Munich 2 (Lucio 72, Klose 74)
Hamburg SV 2 (own goal, Kopilas 17, Petric 37) SV Wehen 1 (Schwarz 85)
Wolfsburg 2 (Dzeko 10, 42) Werder Bremen 5 (Diego 3, 55 pen, Ozil 7, Pizarro 71, 89)