Lightning struck twice at Roland Garros last night as Soderling completed another giant-killing act, 12 months on from his defeat of Rafael Nadal.
And, while Federer benefited from Nadal's demise last year by going on to beat Soderling and end his wait for the grand slam that had eluded him for so long, it is his arch-rival who stands to gain this time around.
Should the Spaniard – now the overwhelming favourite for a fifth French Open crown – go on to regain the title, he will supplant Federer at top of the world rankings. He would also deny – temporarily perhaps – the 28-year-old a record-equalling 286th week as number one.
Federer said: "You just take the defeat as it is – you don't think of the consequences. I really felt like my tennis was good enough to come here and do it again, but that was not the case."
Federer's run of 23 successive grand slam semi-final appearances also came to an end last night, as did his 12-0 record against Soderling, who produced some inspirational tennis to win in four sets and finally end his hoodoo against the Swiss. Soderling admitted he found last night's match easier than last year's final.
"It's difficult playing in your first grand slam final," he said.
"Now I am in there and I've played on the centre court a couple of times, it was a little bit easier this time."
The fifth seed faces a last-four clash with Tomas Berdych, who thrashed Mikhail Youzhny in straight sets on Suzanne Lenglen Court.
Soderling's performance was almost matched in the women's quarter-finals by Francesca Schiavone, who upset No.3 seed Caroline Wozniacki to reach her first grand slam semi-final. The 29-year-old will also become the first Italian woman to appear in the last four of a major since 1954 – before the Open era.
She will take on Elena Dementieva in what will be the Russian's ninth grand slam semi-final, a maiden title still proving elusive.
The last-four line-up in the men's and women's singles was set to be completed today.
Nadal takes on fellow Spaniard Nicolas Almagro on Philippe Chatrier, with the winner playing either third seed Novak Djokovic or Jurgen Melzer.
Serena Williams will aim to capitalise on the exits of sister Venus, Wozniacki and Justine Henin when she plays Samantha Stosur. The winner of that match will face either Jelena Jankovic or Yaroslava Shvedova.