Athens - US powerhouse Justin Gatlin is one race away from a historic 100m and 200m Olympic sprint double.
American Shawn Crawford looks like the most likely threat to Gatlin's bid to become the first man since Carl Lewis in 1984 to achieve the Olympic 100m-200m double.
The 200m final is one of three athletics finals on the programme on Thursday.
In the 400m hurdles, Felix Sanchez aims to stretch his unbeaten run to 42 races and claim the first-ever gold for the Dominican Republic.
Before the marquee events got underway on Thursday night, Karam Ibrahim ended Egypt's 56-year gold medal drought with a triumph in the Greco-Roman wrestling 96kg class.
He beat Ramaz Nozadze of Georgia to claim Egypt's first gold since the 1948 Amsterdam Games.
Honours were shared out at the wrestling arena, as Alexandr Dokturishivili of Uzbekistan won the 74kg title over Marko Yli-Hannuksela of Finland, and Jung Ji-Hyun of South Korea won the 60kg crown over Roberto Monzon of Cuba.
The opening day of taekwondo competition saw Taiwan walk off with both gold medals on offer.
Chu Mu-Yen beat Mexico's Oscar Salazar in the men's under-58kg flyweight final 5-1.
His compatriot Chen Shih-Hsin earlier outpointed world silver medallist Yanelis Labrada of Cuba in the women's under-49kg flyweight final.
They were Taiwan's first gold medals in Athens, but there was more joy for Egypt as Tamer Bayoumi earned the bronze in the men's flyweight class with a win over Spain's Juan Ramos.
Greece's Michalis Mouroutsos, men's flyweight gold medallist in Sydney, had lost to Bayoumi in the quarter-finals and complained about the officiating.
There was disappointment for the host country, too, in women's water polo as Melania Grego's last-gasp goal in extra time gave Italy a 10-9 victory over Greece in the championship match.
It ended the dream run of outsiders Greece, who had fought a tough match from the outset with Kyriaki Liosi scoring five and Evangelia Moraitidou three.
The bronze medal match pitted the Sydney finalists Australia and the United States, with the Americans emerging this time with the win to shut the defending champions out of the medals.
The title was also on the line in women's field hockey, where the Netherlands and Germany set up a gold medal clash with penalty shoot-out wins in the semi-finals.
The Netherlands are seeking to improve on the bronze they won four years ago in Sydney, where the Germans finished seventh.
