Williams, Azarenka to meet in Brisbane final
Serena Williams of the US celebrates after defeating Maria Sharapova of Russia in their women's semi-final match at the Brisbane International tennis tournament in Brisbane on January 3, 2014
Williams, the defending champion, beat Sharapova 6-2, 7-6 (9/7) in one hour, 43 minutes on Pat Rafter Arena.
Earlier, Azarenka recovered from a disastrous first set to beat Serbia's Jelena Jankovic 1-6, 6-3, 6-4.
Williams and Sharapova have a fierce rivalry on the court, which is matched by an at times bitter relationship off it.
They didn't hold back during their semi-final, thrilling the packed stadium with the power and depth of their groundstrokes.
Both women struggled to hold their serves throughout, although Williams was slightly more consistent, breaking Sharapova three times in the first set while losing hers only once, despite making only 40 percent of her first serves.
"I think we are both very strong returners, and personally I couldn't get a first serve in today," Williams said.
"My first serve percentage was extremely low. I didn't serve nearly as well as I served in my first two matches.
"(I was) a little disappointed because that's what I've been working on, being consistent with my serve."
The serving struggles continued into the second set, with three breaks apiece, but both held when it mattered to send the set into a tiebreak.
Williams had match points at 6/5 and 7/6 in the tiebreak, which Sharapova saved, but at 8/7 and on her own serve she blasted an ace down the centre line for her 14th consecutive win over the Russian.
In the first semi-final Azarenka was all at sea in the opening set as she was swept aside by the Jankovic in just 29 minutes.
With her serve misfiring badly, the second seeded Azarenka looked certain of a quick exit, particularly when she went 0-40 down in the first game of the second set.
But she fought her way back to win that game, and from that point the momentum turned as Azarenka began to find her rhythm and Jankovic started to fade.
Azarenka took the second set comfortably then held off a late comeback from Jankovic to win in two hours, five minutes.
"I think we can look at it (the first set) as a struggle, but I don't think that was a struggle -- I think Jelena played really, really well in the first set," she said.
"I felt that I could have done better, but it's just the matter of kind of getting that timing, really fighting through it.
"But I think I was able to change it around in the second set. I really tried to apply the game I wanted to apply, whereas in the first set it was a little bit out, a little bit short."
Williams and Azarenka have met 16 times on the WTA tour with the American holding a 13-3 advantage.
However, they met four times on the court last year with honours even at two wins apiece.
"She's had some tough matches, I've had a few tough matches," Williams said of her clash with Azarenka.
"I think it'll be a really good match to see where we both stand as the two most consistent players of the last year and a half."