Söderling dumped Nadal, who was then the four-time champion, out of the French Open in a four-set last-16 stunner nine years ago.
It ended the Spaniard's 31-match win streak in Paris.
The Swede went on to make the final where he lost to Federer allowing the Swiss to complete the career Grand Slam.
“No, he hasn't thanked me. I'm still waiting,” joked 33-year-old Söderling at Roland Garros on Thursday.
“When he saw I beat Rafa, I think he was a little bit happy, of course. But maybe he could have beat him in the finals. Who knows?”
Söderling made the final as well the following year when Nadal gained revenge to claim a fifth French Open.
The Swede, whose career ended abruptly in 2011 after being diagnosed with mononucleosis, believes that Federer would be playing at Roland Garros if the title was still missing from his Grand Slam collection which now totals 20.
The 36-year-old Swiss has skipped the clay-court season for the last two years, preferring to keep his powder dry for Wimbledon where he is an eight-time champion.
“I think that what changed is that I think if Roger so far hadn't won Roland Garros, I think he still would be playing here.”
“Now he chose to not play at all on clay for the last couple of years, which I think is a good decision, because he really wants to play as long as possible. He's really trying to make his career as long as he can.”
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Söderling also believes that Federer, with his 37th birthday fast approaching, and Nadal, who has just turned 32, are in a race to see who can end their careers with the most Slams.
Nadal will go to 17 if he wins an 11th Roland Garros this weekend, just three behind his longtime rival.
“They're just different persons from all of us,” said Söderling.
“They are still hungry. But I really think that the rivalry between them on court has helped them both. I think maybe that's one of the reasons Roger is still playing, because he feels that, 'Okay, if I retire now or any time soon, if Rafa plays a few more years, maybe he will beat a few of my records'.”
Söderling, who now coaches Swedish player Elias Ymer, won 10 career titles and reached world number four in the rankings.