By Patrick Johnston
SINGAPORE (Reuters) - World number one Serena Williams was handed the best possible draw for her WTA Finals title defense with the 33-year-old American grouped with two injury doubts and avoiding the in-form players.
Williams was pooled in the Red Group on Saturday for the WTA's season ending event alongside Romanian Simona Halep, Canada's Eugenie Bouchard and Serbia's Ana Ivanovic who have managed only one career victory among them against the 18-times grand slam singles champion.
The more competitive looking White Group features Russian Maria Sharapova, Wimbledon champion Petra Kvitova, Poland's Agnieszka Radwanska and Caroline Wozniacki of Denmark.
Williams is gunning for her fifth season ending championships win and third straight, having taken the last two titles in Istanbul.
Her participation in this year's event, which switches to Singapore for the first of five editions, was in doubt after she was forced to pull out of the Beijing tournament earlier this month because of a knee problem.
Bouchard is also a fitness doubt after pulling out of a tournament in Austria 10 days ago because of a leg problem, while Ivanovic, who has a 1-7 win-loss record against Williams, also withdrew from Linz with a hip injury.
Romanian Halep has struggled for form of late and not made it past the quarter-finals of an event since July. The French Open runner-up is 0-3 against the American.
Sharapova, who beat world number three Halep in the final at Roland Garros, has had no such issue with form and was named the WTA's Player of the Month for September after winning the prestigious Beijing title, her last action before arriving in Singapore.
There she beat Kvitova in the final, with the Czech just missing out on back-to-back titles having won the week before in Wuhan.
The two will be favorites to grab the two semi-final berths from the tricky White Group but will face stiff competition from former world number one Wozniacki, who has also shown strong form in the tail end of the season.
The Dane was runner-up to Williams at the U.S. Open, made the finals in Tokyo and the semis in Wuhan to book a spot in Singapore.
The action gets underway on Monday at Singapore's revamped indoor stadium, which forms part of the city-state's new $1 billion Sports Hub.
1-Serena Williams (United States)
4-Simona Halep (Romania)
5-Eugenie Bouchard (Canada)
7-Ana Ivanovic (Serbia)
2-Maria Sharapova (Russia)
3-Petra Kvitova (Czech Republic)
6-Agnieszka Radwanska (Poland)
8-Caroline Wozniacki (Denmark)
(Editing by Amlan Chakraborty)