29 January,2009 10:36 AM IST | | AFP
Second seed Williams again hit form at the right time to reach her 13th Grand Slam decider, ending Dementieva's 15-match winning streak.
The American, who holds nine majors and has won all of the three finals she has contested at the Australian Open, threw off the service problems that have dogged her throughout this tournament.
"I was really calm, I thought if I could add a little more spin and could play like Roger (Federer) there's no way I could lose," she said.
Williams blasted down 10 aces in the Rod Laver Arena, where the roof was closed as Melbourne's worst heatwave in a century continued, while Dementieva's service game fell apart as she committed eight double faults in the second set.
It is the third straight time the Russian has been eliminated in a Grand Slam semi-final and the 27-year-old looked increasingly rattled and at times screeched in frustration as the match progressed.
Dementieva attacked Williams' serve from the outset, setting up two break points in an opening game but failed to covert both when her backhand let her down.
Williams' serves soon found their mark and she had two chances to break Dementieva in the next but neither player could pull ahead.
Every game was a closely contested arm-wrestle until the sixth, when Dementieva held Williams to love for the first time.
It served as a warning to the American, who struggled in the heat during her quarter-final match, and she stepped up her aggression in the next, hitting a venomous forehand down the line as she held serve to make it 4-3.
Instead, it was Dementieva who conceded a break in the next, gesturing in frustration to officials after hitting a forehand wide.
Willaims smacked her sixth ace of the match serving for the first set, with Dementieva again hitting her returns and indicating her racquet strings had loosened in the humidity, a problem that troubled Williams in the quarters.
The Russian conceded the set after 44 minutes.
An intent-looking Williams maintained her focus and brought up two break points in the opening game of the second set but wasted both opportunities when she hit her returns into the net.
The pressure she was beginning to tell on Dementieva, who lost her cool and yelled at herself in Russian.
Dementieva regained her composure and attacked Williams' second serve in the third game, snatching her first break with a forehand down the line then holding serve to go up 3-0.
Williams then held Dementieva to love to get on the scoreboard.
The American brought up break point in the fifth game, falling heavily onto the court as she stretched to get back on level terms with the Russian.
Dementieva then handed her the break with a double fault, screeching with frustration after hitting a return wide in the next as Williams comfortably held serve.
Demientieva lost her sun visor reaching up for a return two games later but gained a break to get back on level terms.
But Williams immediately broke back and sent down two aces as she served out the match.
