Hackett (left) says Phelps can improve on his 2004 efforts
Australian swimming great Grant Hackett believes American Michael Phelps could beat Mark Spitz's record haul of seven gold medals at an Olympic Games.
Australian legend Ian Thorpe has already dismissed Phelps' attempts to win a record eight golds in Beijing.
But 1500m champion Hackett said: "I think Michael is capable of anything.
"If a couple of his competitors are a little bit off in the race and he is a little bit on, he is capable, certainly, of achieving that goal."
Hackett, who is aiming to set a record of his own by becoming the first swimmer ever to win three consecutive 1500m Olympic gold medals, added: "Michael has a tendency to get to the wall and really bring it home."
Phelps fell just short of Spitz's 1972 benchmark when he won six golds and two bronze medals at the Athens Olympics in 2004.
SPITZ'S 1972 GOLDEN HAUL
4x100m freestyle relay
4x200m freestyle relay
4x100m medley relay
He is likely to swim the same events in Beijing he tackled in Athens: the 200m and 400m individual medleys, the 100m and 200m butterflies, the 200m freestyle and the three relays.
Australian head coach Alan Thompson has tipped the US star to go close, but feels the medley relay could let him down.
"I think if anyone is capable, Michael is," he said of beating the Spitz mark. "He's a sensational swimmer.
"Maybe the medley relay is the one that could shut him out, but I think he is probably the best swimmer in the world and certainly he has great depth. He seems to thrive on the more events he has."
Last week Thorpe, Australia's greatest Olympian with five swimming golds from two Games, said he believed that surpassing Spitz' record could not be done.
"I have said I don't think he will win eight gold medals," he said. "I don't think he will.
"But mind you, if there is any person on the planet who is capable, it is him. It's sad, but I just don't think it will happen."