Andy Murray will drag his weary body through another tough test at the ATP World Tour Finals as an explosive season finale draws ever nearer.
Having beaten Marin Cilic and Kei Nishikori, Murray only needs a set against Stan Wawrinka today to guarantee his passage through to the semi-finals at the O2 Arena for the first time since 2012.
That will not be easy in itself, with world number three Wawrinka showing much better form in beating Cilic on Wednesday than he had in his limp loss to Nishikori.
The Swiss, meanwhile, knows that a straight-sets win over Murray would maintain his record of always reaching the last four.
It may not be essential, but Murray has plenty of incentives to win his final group match - not least the knowledge that doing so would mean he could not face Novak Djokovic until the final, setting up a straight shoot-out for the world number one spot.
Victory would also equal the career-best winning run of 22 matches he set earlier this summer.
The Scot needed three hours and 20 minutes to see off Nishikori but was back on court early yesterday morning for a practice session.
He said: "Obviously it's important to win matches to give yourself the best chance to go through.
"Two hundred points for each match here is quite a lot, as well. Obviously that increases as you get into the semis, potentially in the final. It could come down to a match between me and Novak. Who knows what's going to happen the next few days.
"Just from my side, I'll concentrate on trying to win my own matches, get through as many as I can, make it as tough as possible for Novak to jump me."
Brother Jamie and Bruno Soares maintained their perfect record at the ATP World Tour Finals to march through to the doubles semi-finals.
After winning their first two matches, Murray and Soares only needed a set against Ivan Dodig and Marcelo Melo to guarantee a place in the last four.
But they went one better by winning the clash 6-3 3-6 10/6, setting up a semi-final meeting tomorrow against either Raven Klaasen and Rajeev Ram or Feliciano Lopez and Marc Lopez.
It was significant because the 200 ranking points they earned put Murray and Brazilian Soares provisionally ahead of Nicolas Mahut and Pierre-Hugues Herbert in the race to finish the year as the number one team in the world.
Djokovic, meanwhile, made it three wins from three with victory over alternate David Goffin.
The Belgian stepped in after Gael Monfils pulled out on Wednesday with a rib injury to become the third debutant at this year's tournament.
But it was not a happy experience for Goffin, who detained Djokovic for just an hour and nine minutes before the Serbian wrapped up a 6-1 6-2 triumph.
Djokovic said: "I felt most comfortable of all the matches I've played. I felt like I increased the level of the quality of tennis."
Djokovic was already guaranteed to top the group while Goffin had no chance of progressing, but there was still the small matter of nearly £150,000 and 200 ranking points at stake.
The only real moment of unhappiness for the defending champion, who has lost just one match here since 2011, came after he received a time violation in the following game.
Djokovic was furious with umpire Fergus Murphy and also made his feelings known to the tournament supervisor.
In last night's match, Milos Raonic beat Dominic Thiem 7-6 (7-5) 6-3 to book a place in tomorrow's semi-finals against Murray, Wawrinka or Nishikori.