London: Stefanos Tsitsipas beat six-time champion Roger Federer and will now take on Dominic Thiem for the title at the ATP Finals.
The 21-year old Greek won 6-3, 6-4. Austrian Thiem, meanwhile, got the better of defending champion Alexander Zverev 7-5, 6-3 at the 02 Arena here.
Asked what fans could expect from the final, Thiem was quoted by the BBC as saying on Saturday: "A one-handed back-handed final, I guess. We are both offensive players, he is very attractive to watch, I love to watch him and I am looking forward to playing him again."
For the record, Tsitsipas is the youngest finalist since Juan Martin del Potro in 2009.
This final will also be just the third summit clash since 2002 without Federer, Novak Djokovic or Rafael Nadal.