Eight time Grand Slam champion Andre Agassi of the United States has advanced to the semifinals of the Tennis Masters Cup in Houston, Texas, after beating Argentina's David Nalbandian in round robin play.
The fifth seeded American rallied to beat eighth seeded Nalbandian Thursday 7-6, 3-6, 6-4 in a Blue Group match.
In a rematch of last year's Australian Open final, Agassi will take on Germany's Rainer Schuettler Saturday in the semifinals.
Schuettler advanced Thursday after defeating world number one Andy Roddick of the United States in a Red Group match. The German sixth seed came back from being down 0-3 in the decisive third set to beat Roddick, 4-6, 7-6, 7-6.
The ATP Tour honored Roddick, 21, after the match, presenting him with a crystal trophy marking his ascension to world number one. Only Australian Lleyton Hewitt, who was 20 when he was number one at the end of 2000, reached the top at a younger age.
In an another Red Group match, fourth-ranked Guillermo Coria of Argentina defeated number seven Carlos Moya of Spain, 6-2, 6-3.