- Roger Federer will play world No. 1 Novak Djokovic in final of season-ending tournament
- Defending champion Federer beats world No. 3 Andy Murray in Sunday's semifinal
- Federer will be seeking a record-extending seventh title, and his third in a row
- Djokovic beats Juan Martin del Potro to reach final for second time, his first in London
Even after all these years, Roger Federer is still thrilled by the chase.
The 31-year-old cannot regain his No. 1 ranking this year, but he can add yet more accolades to his glittering resume if he beats Novak Djokovic in Monday's climax of the ATP World Tour Finals in London.
The 17-time grand slam champion blew away Andy Murray in Sunday's second semifinal, earning some measure of revenge for his defeat in August's Olympic gold medal match and denying the Scot another long-awaited milestone.
Murray became the first British male to win a grand slam since 1936 when he lifted the U.S. Open in September, but the UK will have to wait for its first finalist in the season-ending showpiece.
"It was a special match. It was the third time in London this year for the two of us and the crowd was electric," said two-time defending champion Federer, who beat Murray in July's Wimbledon final to match Pete Sampras' record of seven titles on the hallowed grass courts.
"I have been around the block a few times and that was something. You can't tire of nights like this.
"That is why I keep practising in front of no people, it inspires you to keep working hard."
At first it had seemed that Federer might have been feeling the effects of Saturday's three-set defeat by Juan Martin del Potro, as Murray -- who had an extra day off -- took an early 3-1 lead.
But the Swiss worked his way back into the match in front of a pro-Federer crowd, and raced away to win 7-6 (7-5) 6-2 in one hour and 33 minutes.
"Almost all the times when you play Roger anywhere in the world he gets great support everywhere. He deserves that because of everything that he's achieved," said Murray.
It was his third semifinal defeat in the elite eight-man event, while last year he pulled out with injury during the round-robin stage.
"It's been the best year of my career by a mile ... I've achieved things I've never achieved before," the 25-year-old said.
Federer will seek a record-extending seventh title, and bid to match the last man to have won it three years in a row -- Murray's coach Ivan Lendl.
He will face a formidable foe in Djokovic, who was guaranteed the year-end No. 1 spot when Federer decided not to defend his Paris Masters title last week.
The Serbian lost his opening match in the French capital soon after his father was taken to hospital with a serious respiratory problem, but better news from home has helped him win all four matches so far this week.
Djokovic was tested by Del Potro in Saturday's opening semifinal, but showed the fighting abilities he needed in earlier group-stage wins against Murray and Tomas Berdych as he prevailed 4-6 6-3 6-2.
The giant Argentine, runner-up in 2009, looked poised to reach the final for the second time as he went a break ahead in the second set but Djokovic turned it around.
He won the 2008 final when the tournament had its final staging in Shanghai, but has never got this far in London.
"Knowing it's the last match of the season, I'm really going to try to give my best physically and mentally tomorrow," said Djokovic, who equaled David Ferrer's leading 74 match victories this year.
Del Potro has won a career-high 65 matches in 2012, battling back into the top 10 after a long recovery from serious wrist problems.
"He deserved to win today. If you don't play for the whole match at your best level, it's really difficult to beat him," Del Potro said.
"I had the chance to win today when I was a break up in the second, but I didn't serve like yesterday and I didn't serve like my first set today. Nole was returning really well."