He may have defeated him 11 times out of 11, but Roger Federer will take nothing for granted when he takes on Robin Soderling in the US Open quarter-finals on Wednesday.
His win streak against the Swede stretches back five years, but Federer says Soderling, a former top junior who has struggled to fulfill his potential on the senior stage, is a changed player this year.
"He has become mentally and physically stronger. And then he knows the game better today than he used to," the top seed and defending champion said.
"These are already three amazing improvements. That's what makes him a great player today."
Federer has good reason to be fullsome in his praise of the 26-year-old Swede as it was his shock win over Rafael Nadal in the French Open that kicked opened the door for Federer to clinch his own immortality in the sport.
Having lost to Nadal four years running in Paris, the feeling was growing that the Swiss star might never complete the career Grand Slam he needed to validate his claim to be the greatest player of all time.
As it turned out, Soderling was the player on the other side of the net on that damp and overcast day in Paris when Federer finally won the French crown.
A month later, Federer regained his Wimbledon title to become the outright Grand Slam title record-holder with 15.
Soderling, who reached the last eight when Nikolay Davydenko abandoned with a thigh strain when trailing 7-5, 3-6, 6-2, admits ruefully that "he beat me a lot of times" but he believes that every dog is due his day.
"We've had a few very good matches, and I had some good chances to actually win in a couple of them," he said.
"So of course, to me, he's the best player of all time, but if I can play well, hopefully I have a small chance."
On paper the Novak Djokovic-Fernando Verdasco quarter-final, also scheduled for Wednesday, is a much more evenly balanced encounter with the fourth-seeded Serb, the 2008 Australian Open champion and the losing finalist here in 2007, going up against the 10th-seeded Spaniard, who has broken through this year with a run into the Australian Open semi-finals.
Djokovic, with new American coach Todd Martin in his corner, agreed that Verdasco was playing the best tennis of his career.
"He has gained a lot of strength. He feels confident on the court," Djokovic said. "He hits the ball very well. He improved his game a lot generally comparing to the last couple of years."
But he feels that his own game is coming around after a slight slump that saw him lose his world No. 3 status to Andy Murray.
"I have had some ups and downs this year, but I believe I can get far in the tournament the way I was playing in the first two rounds and today was very satisfying," he said after his straight-sets demolition of Radek Stepanek in the fourth round.
The other quarter-final ties, which will be played on Thursday, will be decided later Tuesday with Jo-Wilfried Tsonga taking on Fernando Gonzalez, Gael Monfils going up against Rafael Nadal, Juan Martin del Potro against Juan Carlos Ferrero and Andy Murray faced with Marin Cilic.
