Victoria Azarenka extended her winning start to the 2013 season to 13 matches with a 6-3 6-3 victory over Agnieszka Radwanska in the semi-finals of the Qatar Open.
The defending champion was in impressive form against the Polish world No.4 and will now take on great rival Serena Williams in Sunday's final.
Williams needed just 73 minutes to defeat Maria Sharapova 6-3 6-2, five minutes fewer than it took top seeded Azarenka to beat Radwanska.
Williams, 31, is already assured of becoming the oldest world number one when the new rankings are released on Monday, taking the place of Australian Open champion Azarenka.
Azarenka is arguably in better form than Williams, after defending her Australian Open title last month. However, Williams will surpass her with fewer rankings points to defend.
Williams will beat the previous record set by Chris Evert, who was 30 years and 11 months when she was number one in November 1985.
Azarenka has won only one of 12 meetings against Williams but is determined to focus only on herself tomorrow.
"I just have to be consistent and really focused on my own game," she said.
"We all know she has a great serve. She's really aggressive and really consistent. So for me it's important to just focus on myself and execute my game. That's it."
Williams said she was looking forward to trying to win this tournament for the first time.
She said: "I love it here in Doha. I've never played this particular tournament but I've played in Doha before and had some good results, and I hope to have a good result in the final tomorrow, too."