MELBOURNE: US Open champion Juan Martin del Potro has been named as an alternate player for the Kooyong Classic exhibition tournament here in January, organisers said on Tuesday.

Argentina's Del Potro, 21, is on standby to play if world number one Roger Federer does not take up the eighth and final place in the draw for the January 13-16 warm-up tournament ahead of the Australian Open, organisers said.

"If Roger decides against playing at Kooyong, or another player withdraws before the tournament, Juan Martin will step into the field," tournament director Colin Stubs said.

"I am delighted that such strong back-up plans have been put in place."

Other confirmed signings for the Kooyong Classic are Novak Djokovic, Jo-Wilfried Tsonga, Fernando Verdasco, Robin Soderling, Fernando Gonzalez, Tommy Haas and Marcos Baghdatis.