The defending champion is on collision course with Lleyton Hewitt, the man whose title he took.
Both lost in the opening round of the at the Stella Artois Championships.
But fellow Argentines Gaston Gaudio and the indefatigable Guillermo Coria won in straight sets as did Russian Marat Safin
Coria will play Rafael Nadal in the final of the Rome Masters.
Top seeded Roddick beat Austria's Jurgen Melzer while Grosjean scored over Nicolas Lapentti in the semi-finals of the U.S. Men's clay court championships.
Top seed Andy Roddick blasted his way into the last four with a 6-4, 6-1 victory over Peru's Luis Horna.
Defending champion Tommy Hass also moved into the second round at the US Clay Court Championships.
The Russian had his endurance tested to the limit by the German before coming through the first round of the Australian Open.
The 26-year-old has already done enough to replace Tommy Haas as the\n\nGerman No. 1 when the latest world rankings are released on Monday.
Andre Agassi says his toe injury will not stop him from playing in the Nasdaq-100 Open, a tournament he has won a record six times.
Defending champion Thomas Johansson of Sweden is injured and won't be defending his title at the Australian Open.
Roger Federer claimed a 6-3 6-1 victory over a shell-shocked Andre Agassi on Saturday to reach the final of the Dubai Open.
Croatia's Ivan Ljubicic upset third seed Tim Henman rain disrupted match to reach the semi-finals of the Dubai Open
Roger Federer added yet another record to his vast collection when he guaranteed becoming the oldest ATP world number one by beating Dutchman Robin Haase 4-6, 6-1, 6-1 to reach the semi-finals in Rotterdam on Friday.
Andre Agassi retained his majestic touch to crush German Rainer Schuettler 6-3, 6-1, 6-0 in Melbourne.
