Roger Federer says thinking about winning his 100th singles title would only add extra pressure before his ATP Finals semi-final against young German Alexander Zverev at the O2 in London.
Federer is aiming to become only the second man - after American Jimmy Connors - to reach the landmark.
"I won't let that get in my head," said the 37-year-old Swiss.
The second seed faces Zverev at 14:00 GMT on Saturday before Novak Djokovic and Kevin Anderson meet at 20:00.
The winners meet in the final of the season-ending tournament at 18:00 on Sunday.
|Saturday's order of play|
|Afternoon session - 12:00 GMT|
|Jamie Murray (GBR)/Bruno Soares (Bra) v Mike Bryan/Jack Sock (US)|
|Roger Federer (Sui) v Alexander Zverev (Ger)|
|Evening session - 18:00 GMT|
|Pierre-Hugues Herbert/Nicolas Mahut (Fra) v Juan Sebastian Cabal/Robert Farah (Col)|
|Novak Djokovic (Ser) v Kevin Anderson (SA)|
Federer lost his opening match with a below-par performance against Kei Nishikori, before returning to form in straight-set wins over Dominic Thiem and Kevin Anderson.
"I'm happy that this is another week like this," said Federer, who is looking to claim a record-extending seventh ATP Finals title.
"It didn't look like it, but I was able to come back and play good tennis.
"Personally I'm still not thinking of the number 100.
"I won't let it make me go crazy because it should be something I'm excited about and not something I should feel extra pressure.
"As long as I think Novak is in the draw anyhow, he's playing so good again, it's never going to be easy."
Djokovic 'knows what to expect' in rematch of Wimbledon final
Djokovic is seen as the man to beat at the O2 after a remarkable run which has seen him win 34 of his past 36 matches.
The Serb was outside of the world's top 20 in June, but rediscovered his form to win the Wimbledon and US Open titles and going on to reclaim the world number one ranking.
Djokovic, 31, earned his first Grand Slam title in more than two years by beating Anderson at Wimbledon and will be the favourite to win the rematch at the O2.
"Kevin is playing some great tennis, it's definitely his best season and he's continued doing that throughout this tournament," said Djokovic.
"He's playing well, serving well, very aggressive, so I know what to expect."
Murray and Soares eye first final
Britain's Jamie Murray and Brazilian partner Bruno Soares bid for their first appearance in the ATP Finals showpiece when they open semi-finals day against American pair Mike Bryan and Jack Sock at 12:00 GMT.
Murray and Soares, who have lost in the last four in each of the past two years, won their group with a 100% record of three victories.
"We're happy to be in the semi-finals, the first goal at the start of the week is getting out of the group, no matter how you do it," said the 32-year-old Scot.
Brazilian Soares also lost in the 2013 semi-finals alongside Austrian Alexander Peya.
"It's about time I went one step further," said the 36-year-old Brazilian. "I guess this is the year to go a couple more."