The team, who has openly admitted it's lacking speed with the MP4-24 car, showed better pace on the final days of testing of the season earlier this week.
But going into the first race of the year, Whitmarsh has made it clear the team's problems are not yet solved, and said its goals remain realistic.
"We go into the start of the 2009 season fully aware that we do not yet have the technical package that will allow our drivers to fight at the front," said Whitmarsh in a team preview.
"In Formula 1, there is nowhere to hide: that's what makes our sport so demanding and yet so endlessly fascinating.
"And as a team that goes grand prix racing with the expectation of winning races and challenging for world championships, we therefore go to Melbourne with realistic expectations.
"Nonetheless, we begin our season with huge determination to re-assert ourselves at the front and we will not rest for a moment until we have done that. Most importantly, we haven't forgotten how to win."
World champion Lewis Hamilton is also aware that McLaren is not in the best position to fight at the top in Melbourne.
"Despite weeks of winter testing, it's still difficult to know exactly who has the best package, and finding out over the weekend in Albert Park is always fascinating," he said.
"Perhaps McLaren doesn't come to Melbourne with the same prospects to challenge at the front that we experienced in both 2007 and '08, but the whole team will be working tirelessly to help us move back to the front."