GSTAAD, Switzerland: Roger Federer`s worrying slump continued Thursday when he was knocked out of the Swiss Open by world number 55 Daniel Brands in another shattering blow just a month out from the US Open.
The German spoiled former world number one Federer`s return to the tournament after nine years with a shock 6-3, 6-4 second round upset.
World number five Federer has won only the Halle title this season after claiming his 17th Grand Slam title at Wimbledon in 2012.
Last week, the 31-year-old was stunned by Argentine qualifier Federico Delbonis, the world number 114, in the Hamburg semi-finals.
That defeat came just a month after Federer was knocked out of Wimbledon by Ukraine`s world number 116 Sergiy Stakhovsky in the second round.
That brought to an end a run of 36 consecutive Grand Slam quarter-final appearances for the Swiss.
Thursday`s 65-minute upset left Federer scrambling to find some form ahead of the US Open in four weeks` time.
His build-up for the season`s final Grand Slam event of the year in New York begins at the Montreal Masters from August 5.
Federer had made a celebrated return to the small claycourt tournament at Gstaad where he got his start on the ATP Tour 15 years ago as a teenaged wildcard entry.
He lost in the first round in each of his first four appearances, from 1998 through 2001.
The fifth-ranked Swiss -- his lowest standing in a decade -- was competing in this elite alpine village at 800 metres nine years after last appearing in a title-winning performance.
Brands came good on the threat he posed in the Hamburg first round eight days ago when he lost in three sets to Federer.
This time, the German got the win despite Federer saving two match points, the first with an ace on his own serve in the ninth game of the second set.
Brands completed the fourth win of his career over a top 10 player a game later after Federer, who struck more than 20 unforced errors, saved another match point before falling to a Brand service winner.
"This is a really special win," said Brands.
"I played at 100 per cent, I didn`t have a big strategy, I just played point after point and tried to stay strong mentally."
The German will next face Victor Hanescu, who advanced to the quarter-finals when Spanish eighth seed Roberto Bautista Agut retired with back pain trailing 7-6 (7/2), 3-2.
Serb third seed Janko Tipsarevic was knocked out in his opening match 6-2, 6-2 by Dutchman Robin Haase.
Tipsarevic has had a dreadful showing this season, slipping out of the top 10 over the last four months.
He began in January with a title in Chennai but has since managed only three quarter-finals.
The number 18 had no answer to Haase, playing the tournament for the first time and now standing 16-18 this season and now one victory away from a 100th career success.
Tipsarevic went down two breaks in the second set and managed briefly to stop the rot before eventually falling in 61 minutes with six double-faults and dropping service four times.
The 2011 Gstaad winner, Marcel Granollers, moved into an ATP quarter-final for the third time this season with a 6-2, 7-5 second-round elimination of Delbonis, the runner-up in Hamburg last week.
Granollers, one of eight Spaniards to win the title in the post-1968 Open era, claimed victory over the 65th-ranked Delbonis -- he stood 114th last week -- in 96 minutes.