Belarussian Victoria Azarenka returns a ball to Poland's Agnieszka Radwanska
Victoria Azarenka booked her place in a second straight final at the Madrid Masters after stretching her 2012 winning streak over Agnieszka Radwanska to six matches this season with a 6-2, 6-4 victory on Saturday.
The world number one will play for her fifth title of the season when she takes on number nine seed Serena Williams, a 7-6 (7/5), 6-0 winner over Czech qualifier Lucie Hradecka.
Azarenka has tasted victory in just one of seven matches with Williams, who won their last meeting at the 2011 US Open.
Azarenka has lost just one set of 14 played this season against Radwanska and now leads 11-3 overall in their head-to-head series.
The Belarusian top seed advanced in 79 minutes with 29 winners and six breaks of serve, sealing the win on her second match point with a drop-shot that Radwanska could not reach.
"I'm very happy to reach another final. That is always the goal," said the winner. "I've had a lot of good matches this week.
"I'm glad to be back in the final. I'm looking forward to it."
Azarenka will be out to prove herself after losing the 2011 final here to Petra Kvitova, two months before the Czech made her major breakthrough by winning Wimbledon.
She has four trophies this season, but will be aiming for her first of the year on clay, having last triumphed on hardcourt at Indian Wells in March.
The Belarusian, who began the season with 26 consecutive wins, stands 34-2 for the season, with her only defeats coming against Marion Bartoli in Miami and against Maria Sharapova in the Stuttgart clay final last month.
Radwanska was playing with her new world ranking of third as she competed in her sixth semi-final of 2012.
Williams advanced to the final without facing a break point against Hradecka, sweeping the last set to end with 19 winners.
"I'm feeling good," said Williams. "We both served really well.
"She did everything well in the first set, but I was able to come through in the tie-breaker. I relaxed and made less errors and more shots.
"I'm ready going into this final. Victoria has played consistently all year; nearly perfect. I'm just going in with nothing to lose. She's the top-ranked player and the favourite."