The Zurich Open women's event opened this year without two popular crowd-pullers – defending champion Maria Sharapova of Russia and Switzerland's Martina Hingis.
Sharapova withdrew on Sunday – the eve of the tournament - with a lingering shoulder injury, while Hingis pulled out with a recurring hip problem that has ended her season.
World number one Justine Henin from Belgium is top seed at the event, which is Europe's most important indoor women's tournament with prize money of $1.3 million (SFr1.53 million).
Henin was champion on her last visit to the Hallenstadion and has eight title triumphs this year, including Roland Garros (France) and Flushing Meadows (United States).
Other seeds include Svetlana Kuznetsova of Russia, Jelena Jankovic and Ana Ivanovic of Serbia, and Serena Williams of the US. Patty Schnyder and Timea Bacsinszky will be flying the flag for Switzerland.
There are increasing doubts whether Hingis, who lives in canton Schwyz, will return to the courts to play top-level tennis.
It was in Zurich where Hingis played the first professional tournament of her career. She won there in 2000, became an ambassador for the event during three years of absence from the courts, before reaching the quarter-finals in 2006.
"I'm very disappointed that I have to withdraw from the Zurich Open and that I can't play in front of my home crowd," Hingis said.
"I've done everything I can to be able to compete, but since Key Biscayne I've had problems with my hip, and they're still stopping me from playing any more tournaments this year and even from practising properly. I've therefore decided that I'm going to take as much time as it needs to get fully fit again."
There are several question marks over Hingis's career. In the best scenario, the former world number one will play again in January at the Australian Open, which she has always enjoyed.
In the worst case, it could spell the end of her career because it is hard to imagine Hingis doing battle on the courts to reach only the quarter-finals or the third round of Grand Slam events, as was the case at Wimbledon or the US Open this year.
Hingis began the year well. She was a finalist at Gold Coast in Australia, then quarter-finalist in Melbourne and won in Tokyo. The signs were that she was back among the top players. Her sixth position in the world rankings looked like a stepping stone to further successes.
But this was not to be. Compatriot Schnyder humiliated her in May in Berlin (6-4, 6-0), with Hingis suffering from persistent hip and back problems which forced her to give up hopes of the French Open in Paris.
Her doctor Heinz Bühlmann appeared to be reassuring, explaining that there was "no chronic pain but an injury linked to a accumulation of strain".
The fact is that since the spring, Hingis has taken part in tournaments only sporadically.
Her appearances at Wimbledon and Flushing Meadows resulted in defeats by lesser players and at the end of September – her last attempt – she suffered a humiliating second-round exit in Beijing.
swissinfo, based on an article in French by Jonathan Hirsch
Following the draw for the event at the weekend, Schnyder (ranked 15th by the Women's Tennis Association) will play the American Serena Williams (WTA 6) in the first round.
Compatriot Timea Bacsinszky (WTA 88) played Alona Bondarenko (WTA 25) from Ukraine on Monday night in her first round match, losing 1:6 6:3 6:3.
The tournament at the Hallenstadion, which has seating for 6,200, lasts until October 21.
Sharapova won last year's event beating Hantuchova 6-1, 4-6, 6-3.
The first Zurich Open was staged in 1984.