Roger Federer stands between Novak Djokovic and a fourth successive title at the ATP World Tour Finals after the former beat Stan Wawrinka 7-5 6-3 on Saturday.
It was Federer who ended the world number one's 23-match winning streak during the round-robin phase of this competition.
And the Swiss master will now have the chance to inflict another defeat on Djokovic after coming from a break down in the opening set of his semi-final to ultimately beat compatriot Wawrinka with a degree of comfort at London's O2 Arena.
Wawrinka was initially able to counter the typically aggressive approach of an opponent who came to the net on a regular basis, and it was the fourth seed who broke first in the opening set.
However, although Wawrinka initially held with ease, a sloppy service game allowed Federer to level at 4-4 and all the momentum was with the 17-time grand slam champion thereafter.
A run of five straight games saw Federer take the opening set and seize command of the second, amid a notable absence of long rallies.
Wawrinka saved one match point when serving at 5-2 down, after Federer had got to deuce by hunting down a superb drop volley to take arguably the point of the match.
However, that only delayed the inevitable and the contest was brought to a swift end as Federer held to love.
Federer  bt Wawrinka  7-5 6-3
Federer - 6
Wawrinka - 6
BREAK POINTS WON
Federer - 3/6
Wawrinka - 1/2
FIRST SERVE PERCENTAGE
Federer - 64
Wawrinka - 61
PERCENTAGE OF POINTS WON ON FIRST/SECOND SERVE
Federer - 75/65
Wawrinka - 69/41
Federer - 72
Wawrinka - 55