Roger Federer is unlikely to make the same mistake as in 2002, when he was stunned in Wimbledon's first round after taking lofty Croat Mario Ancic for granted.
It was the last time five-times champion Federer lost on grass and it taught the world number one a lesson he will remember when he meets the 1.96-tall Ancic in the quarter-finals on Wednesday.
"I completely underestimated him when I played him," Federer said. I played a great Wimbledon the year before, came in as maybe top five, six seeds...
"I got completely surprised. He played well till the very end. I was a little shell-shocked and didn't know what happened to me," said Federer, who has beaten Ancic in all-five meetings since then.
"What it taught me was not to underestimate any opponent, no matter where they're from, what technique they have, what ranking they have."
In confessional mood after putting out former number one and 2002 champion Lleyton Hewitt in the fourth round, Federer added: "I think I had a tendency to sometimes, when guys maybe didn't have the proper technique or were new on tour, I would sometimes not give them the respect maybe they deserved."
Ancic, nearly three years younger than Federer, was only 18 when he put the Swiss out, little knowing the victory would be cited time and again over the next six years as Federer took a grip on Wimbledon and the number one ranking.
Ancic, unseeded this year after suffering a severe bout of glandular fever which put him out of action for six months in 2007, did not match Federer's meteoric rise, though he matured into a dangerous opponent on fast courts.
He reached a highest ranking of seven in 2006, the year he made the French Open and Wimbledon quarters, losing to Federer both times, and is now 43rd.
Ancic has accounted for three seeds this Wimbledon in number 32 Michael Llodra, number five David Ferrer and number 22 Fernando Verdasco, a Frenchman and two Spaniards who are much more comfortable on the red clay.
He has had to battle through two five set matches where Federer has yet to drop a set.
Ancic knows there is a world of difference between Federer in 2002 and Federer in 2008 with an unbeaten run of 63 grasscourt matches behind him.
"He was not Roger Federer at that time. I can sit here and talk stories about how great the win was and how I beat Roger Federer but actually it wasn't Roger Federer as we know him today," said the personable Croat, who most recently lost to the Swiss in the French Open third round a month ago.
"I think from the year after he won Wimbledon he exploded and today he's completely different player.
"We played...after that. He beat me. Of course it's unbelievable, because since then he hasn't lost on grass. But if it was not for that, I think people would pretty much forget about that win."
