(CNN) -- Group B outsider Robin Soderling became the first player to reach the semifinals of the season-ending ATP World Tour Finals on Wednesday night.
The Swede shocked defending champion Novak Djokovic 7-6 (7-5) 6-1 in the afternoon match for his second successive win, and then was handed a place in the last four when Nikolay Davydenko upset world No. 2 Rafael Nadal 6-1 7-6 (7-4) in the evening.
The 25-year-old only qualified for the tournament as a reserve after Andy Roddick pulled out injured, but Djokovic has backed him to go even further in his first appearance at the eight-man event, which has moved to London this year.
"He has nothing to lose," the Serbian told the official ATP Tour Web site. "He won four straight sets and absolutely deserved to qualify for the semifinals. I think he's the best player so far in the tournament."
Soderling is the first Swede to reach the semifinals since Jonas Bjorkman at Hannover in 1997, and it is the fourth time in the past five years that the eighth seed has reached the last four or better.
"It's great. I mean, I won two matches in straight sets against the World No. 2 and No. 3. I couldn't have asked for anything more," the French Open finalist said.
"So far I'm enjoying it a lot. But there's still at least two more matches to go. I hope to do really well in those two as well."
Ahead of the Soderling-Djokovic match, Roger Federer was presented with a trophy by ATP chairman Adam Helfant after he clinched the year-end No. 1 ranking with his victory over Andy Murray on Tuesday.
That clash was played in a raucous atmosphere at a packed O2 Arena, and it was inevitable Wednesday's encounter would be a more sedate affair, although the attendance was still impressive.
Soderling had played exceptionally well in his win over Nadal on Monday, with his bullet forehand proving particularly troublesome for the Spaniard, but it was more hit and miss in the early stages this time around.
The eighth seed needed four huge serves to avoid being broken in the third game but he was then presented with a golden opportunity to clinch the first set in game 10.
Twice Nadal had faltered at 4-5 against Soderling and it looked like history would repeat itself only for Djokovic to recover from 0-40 -- a mammoth rally at deuce finding the world number nine unable to break his opponent's resistance -- to hold.
Into the tie-break they went and there were mini-breaks aplenty before Djokovic finally succumbed to his opponent's power to go down 7-5.
The world No. 3 had beaten Soderling in all five of their previous meetings, including in Paris two weeks ago in a result that looked like denying the Swede a place in the tournament.
Indeed, Djokovic came into the event as arguably the man to beat after back-to-back titles in Basle and Paris, but he has also had the heaviest schedule of the top contenders this year and a three-set epic against Nikolay Davydenko on Monday night did not help.
The 22-year-old admitted afterwards he was running on empty and his task became even harder when he was broken in the third game of the second set, Djokovic failing with an attempted drop shot at the end of a titanic rally.
The Serb looked resigned to his fate and he surrendered his serve for a second successive game as Soderling surged into a 4-1 lead.
Djokovic battled hard in an attempt to force his opponent to serve out for victory, saving one match-point with a backhand winner, but a netted volley sealed his fate.