Serena Williams of the US celebrates after defeating compatriot Madison Keys in their women's singles semi-final match at the Australian Open 2015 tennis tournament in Melbourne January 29, 2015. [Photo/Agencies]

MELBOURNE - Serena Williams weathered a barrage of big serves and heavy groundstrokes in the first set before beating 19-year-old Madison Keys 7-6 (5), 6-2 to set up an Australian Open final against Maria Sharapova.

Williams dominated the second set of the all-American semifinal, breaking Keys' serve twice. Keys saved seven match points on serve in the penultimate game before Williams closed with an ace on her ninth match point.

Sharapova beat fellow Russian Ekaterina Makarova 6-3, 6-2 earlier Thursday.

Williams, an 18-time major winner, is back in the final here for the first time since winning her fifth Australian title in 2010.

The win ensured Williams will retain the top ranking, regardless of the outcome against No. 2 Sharapova. The American has a 16-2 record against Sharapova, including the last 15.