ATP World Tour Finals
Venue: O2 Arena, London Dates: 21-28 November
Coverage: One match each day live on BBC TV, streamed online & available through iPlayer; text commentary online and on mobiles for every singles match via BBC Sport website; every singles match live on 5live sports extra.
Djokovic bounced back from defeat by Rafael Nadal with a comfortable win
By Piers Newbery at the O2 Arena
Novak Djokovic ensured that the four players who will head the world rankings at the end of 2010 made it through to the semi-finals of the end-of-season championships with victory over Andy Roddick.
The Serb, ranked third in the world, needed to win only one set in his final round-robin match to progress from Group A at the ATP World Tour Finals, but in the event saw off an exhausted Roddick 6-2 6-3 in 65 minutes.
Djokovic will now face world number two Roger Federer at 2000 GMT on Saturday, after world number one Rafael Nadal plays Andy Murray - who has guaranteed he will move up to at least fourth in the rankings next week - at 1400 GMT.
The last two times I've lost against Roger, but they were close matches so I'll try to step it up,
"It's a great achievement reaching the semi-finals," a delighted Djokovic said. "It's great for the tournament to have the top four guys in the semis. It's a big challenge for all of us."
Roddick required a straight-sets win to overhaul Djokovic for a semi-final place and had reason to be hopeful after winning their last four matches for the loss of only one set.
Djokovic has always struggled to read the American's huge serve and needed no repeat of the severe difficulties he had with a contact lens in his previous match against Nadal.
Ever the crowd-pleaser, the 23-year-old Serb made it very clear on Friday night that the problem had not lingered by walking into the arena wearing an eye patch.
He quickly had to get his mind on the job in hand as some Roddick sliced backhands in the opening game caused him problems, but the American put a backhand into the net on break point and from that moment his challenge effectively ended.
After a couple of straightforward service games, Roddick made a double-fault and a backhand error on his way to losing a 30-0 lead before spraying a forehand into the tramlines on break point.
The match slipped away very quickly from then on, a couple more forehand errors giving up a second break and with it the set in game eight, and the American appeared to pull up with a physical problem as he slipped break point down in game four of the second set.
A double-fault gave Djokovic a 3-1 lead and the Serb eased to victory, sensibly keeping his increasingly immobile opponent moving from side to side and throwing in the odd drop shot.
The 17,000 spectators gave Roddick plenty of encouragement when he managed to find the occasional winner but, after a little over an hour, Djokovic put the American out of his misery to set up a repeat of his dramatic US Open semi-final against Federer.
"I think my confidence since Wimbledon is very high and I've played very good tennis and made a lot of good results," Djokovic said.
"Yes, the last two times I've lost against Roger, but they were close matches so I'll try to step it up, take my chances and I hope to prevail.
"The last couple of matches we played were very close so it will probably be similar tomorrow. It's great for the tournament to see us playing in the semi, and on the other hand Nadal and Murray.
"It's a great achievement that I reached the semi-final and I don't think that energy-wise I'm feeling weak and that will be an issue tomorrow."
Roddick admitted that he had simply run out of gas at the end of a long season that saw him struggle with illness and injury, before a late charge in the indoor season to qualify for London.
"I am looking forward to resting for 10 days and then trying to get in shape," the 28-year-old from Nebraska added. "It's been a tough battle between trying to get healthy, working and not getting hurt.
"It's been a tough six or seven months since the beginning of May and tonight's not a whole lot different. It probably came to an end at about the right time and I'm looking forward to trying to get right physically before the Australian Open."