Roger Federer found himself in danger of a rare second successive defeat on Tuesday before recovering to beat Germany's Michael Berrer 6-1, 3-6, 6-3 in the opening round of the Swiss Indoors.
Following his surprise loss to David Nalbandian in Sunday's Madrid Masters final, the world number one had seemed back to his ferocious best as he ripped through the opening set.
Beginning the defence of his hometown title with two aces and two service winners, the Swiss dropped just three points on serve while twice breaking his left-handed opponent.
But Federer then found himself trailing 4-0 in the second set after a string of uncharacteristic errors combined with some bold strokes by the world number 56.
Federer broke back in the next game but was unable to salvage the set.
Faced with the prospect of losing two successive tour matches for the first time since May 2003, the world number one was rescued when Berrer double-faulted at break point to fall 4-2 behind.
Federer still struggled to kill the match off and was taken to deuce at 5-3 before finally serving out with an ace and a service winner.
LAUGHABLE
"It's almost laughable that I have to explain why I lost a set," Federer said in an on-court interview.
"The balls are quite a bit slower here than in Madrid but I'm sure I'll get used to it and play better in the second round.
"Now I'm through the first round and I have a day off on Wednesday -- so everything is perfect really."
Federer was also looking on the brighter side of his defeat to Nalbandian.
"I told myself afterwards it was better to lose in the tournament final than in the first round," he told a post-match media conference. "And I played well all week in Madrid, so now I've just put it behind me.
Second-seeded Chilean Fernando Gonzalez also faced some early problems before winning his first-round encounter with French qualifier Jerome Haehnel.
The world number eight had to defend a set point in the opening set against the world number 242 before taking the subsequent tie-break and an eventual 7-6 6-4 victory.
FERRER FALLS
Spanish third seed David Ferrer and Argentine seventh seed Juan Ignacio Chela both failed to join Federer and Gonzalez in the second round.
Ferrer was upset 6-4, 7-6 by Argentine world number 51 Agustin Calleri while Chela was beaten 6-3, 6-4 by Austrian world number 55 Stefan Koubek.
Despite his defeat, Ferrer remains in strong contention to qualify for the season-ending Masters Cup.
The Spaniard is sixth in the race for the event's eight qualifying berths.
He is also a comfortable 97 points ahead of ninth-placed compatriot Tommy Robredo, who cannot pick up any additional points this week after suffering his own first-round defeat in Lyon on Tuesday.
The picture is looking less bright for Chela, whose own slim hopes of a Masters Cup place all but disappeared on Tuesday.
To have any chance of reaching the Shanghai tournament, Chela would have to make the semi-finals of next week's Paris Masters and hope a lot of other results go his way.