An American, Dutch and Russian astronaut were preparing for their lift-off on Monday toward the International Space Station from Moscow's launch pad in Kazakhstan.
"Everything up till now has gone off as planned," Sergei Gorbunov, spokesman for Russia's Rosaviakosmos space agency, told AFP.
"The cosmonauts feel very well."
US's Edward Michael Fincke, Dutchman Andre Kuipers and Russia's Gennady Padalka are due to blast off aboard a Soyuz rocket from the Baikonur cosmodrome at 9:18 am (0318 GMT) on Monday.
They are due to dock at the station two days later, where Fincke and Padalka will replace Michael Foale and Alexei Kalery who have been there since last October.
Padalka and Fincke are due to remain at the station for six months, and are to perform two space walks in June and August to install equipment necessary for the Jules Verne, a European-built new automated transfer vehicle, which is due to arrive at the station in April 2005.
Kuipers, a Dutchman who will be making his maiden voyage into space on behalf of the European Space Agency (ESA), will stay at the ISS for nine days before returning to Earth with Foale and Kalery on April 30.