LONDON (AFP) Swedish fourth seed Robin Soderling defeated Spains David Ferrer 7-5, 7-5 on Tuesday to keep alive his bid to reach the semi-finals of the ATP World Tour Finals. Soderling and Ferrer had both lost their opening Group B matches in the prestigious end-of-year event at Londons O2 Arena, so the loser of this clash was almost certain to be eliminated. It is the former French Open finalist who remains in with a chance of reaching the last four if he can beat Roger Federer in the last round of group matches on Thursday. However, Soderlings win also meant Federer needs a victory from that game to be sure of qualifying himself, so the Swede wont be overly confident of making it through just yet. Soderling said: It was an okay match. I served very well, especially in the first set. But it was a close match, two really tough sets. Im lucky that I won. I still feel that I have a lot of things that I can improve. Hopefully I can do that. This was a really important win. Now at least I have the chance to make it to the semis. Ferrer, the seventh seed and 2007 Tour Finals runner-up, will face Andy Murray knowing his fate is all but sealed already. He added: I tried to do my best. I fought to win the second set. But Robin played better than me and he had more chances all match. He served really well. After playing each other five times already this year, these two could have been forgiven for being sick of the sight of each other. Soderling had the slight edge with three wins and he arrived in London full of confidence after his victory at the Paris Masters earlier this month lifted him to a career-high fourth in the world rankings. The 26-year-old has often thrived in indoor events but he had been well below par during a comprehensive defeat against Murray on Sunday. He was back to something like his best this time. Following Federers sublime display against Murray earlier in the day, this was a rather more prosaic encounter. The opening stages of the first set were comprised mostly of gruelling baseline rallies, so it was something of a surprise when Ferrer saved a break point in the sixth game by flicking a fine volleyed winner. That was a rare moment of artistry in a hard-fought but uninspiring set which Soderling took when he converted the third of three set-points on Ferrers serve with a superb forehand winner down the line. Soderling was starting to find his range with that booming forehand now and, after missing a break point at the start of the second set, he pressured Ferrer into more mistakes as he broke in the sixth game. To his credit, Ferrer kept going and from 5-2 down he recovered to level the set after breaking Soderling as the Swede served for the match. But, just as a comeback seemed on the cards, Ferrer sprayed a forehand wide to give Soderling a match-point which he gleefully accepted thanks to another error from the Spaniard.