Bolt and Gay close on 100 metres showdown

Usain Bolt of Jamaica (R) and Gerald Phiri of Zambia run in the ninth men's 100 meters heat during the world athletics championships at the Olympic stadium in Berlin August 15, 2009.

BERLIN (Reuters) - Usain Bolt should finally meet Tyson Gay over 100 metres in the centerpiece of Sunday's second day of the world championships.

The world's top two sprinters have not raced this year and both triple Olympic gold medallist Bolt and double world champion Gay are predicting stunning times if the weather stays fine.

Bolt holds the world record of 9.69 seconds, which he set at the Beijing Olympics last year, and American Gay has the season's fastest time, 9.77 seconds.

Former world record holder Asafa Powell could also be in the mix after qualifying fastest from the second round.

Golds will also be up for grabs in three women's events, the heptathlon, shot put and 20km walk.

Britain's Jessica Ennis holds the overnight lead in the heptathlon with New Zealand Olympic and world champion Valerie Vili the shot put favorite.

Russian Olga Kaniskina will be favorite in the women's walk. She has won the last two global titles, winning the world championships in 2007 and the Olympics.

(Editing by Ed Osmond)