Roger Federer is looking forward to renewing his rivalry with Andy Murray in a blockbuster clash at London's O2 Arena on Tuesday night.
The pair meet in Group A of the ATP World Tour Finals both boasting one win apiece and knowing the victor could secure a place in the semi-finals of the lucrative end-of-season tournament.
Murray has been one of the world No.1's most troubling opponents, with the Scot winning six of their nine ATP Tour clashes.
Federer won their biggest match, in the US Open final last year, and also their most recent meeting in Cincinnati but Murray can draw on memories of victories in Indian Wells and Doha this year as well as in the group stages of this event 12 months ago.
On that occasion the 22-year-old triumphed in a three-hour epic in Shanghai that eliminated four-time champion Federer but drained Murray ahead of his semi-final with Nikolay Davydenko, which he then lost.
Recalling the meeting, Federer said: "I remember I was not going into the match with, let's say, the highest of hopes. I kind of just said to myself, 'You know what, I'll play aggressive and see what happens'."
"I was playing incredible for a set, almost got a victory. But I thought it was a very exciting match to be a part of. It was unfortunate for me not to come through."
"I hope we can live up to the expectations and play another good one. Obviously I expect a difficult match. It's always fun playing your rivals."
In Monday's matches, Robin Soderling pulled off the first shock of the tournament with a 6-4 6-4 victory over world No.2 Rafael Nadal.
The Swede, who only qualified for the tournament because Andy Roddick withdrew, was also the man who ended the four-time champion's winning run at the French Open this year and, after climbing into the top 10, he believes he is now becoming a real threat to the biggest names.
"I think I managed to play really well in the important points, which is something I think you have to do if you want to beat the top guys," he said.
"I played a lot of big matches this year, and I played well. I beat a lot of good players."
In contrast, Nadal lost the match primarily because he played poorly on the key points, Soderling breaking at 5-4 in both sets courtesy of sloppy errors from his opponent.
With matches against Novak Djokovic and Nikolay Davydenko to come, the Spaniard is still well in contention for the semi-finals but, having admitted he is low on confidence, he let slip his expectation that he will only play two more matches at the tournament.
"I know, to be ready next year, I'm going to have one month, and these two matches," he said, before quickly adding: "Maybe more."
In the late match, defending champion Djokovic battled to a 3-6 6-4 7-5 victory over Davydenko in a near three-hour epic that was a repeat of last year's final.
The Serbian faces Soderling on Wednesday night and, despite coming into the tournament as the form player, he played down his chances.
Djokovic said: "Generally I'm very exhausted because of the long season. I wouldn't rate myself as a favourite in that match because he's in great form. It's going to be a tough one."