( CNN ) -- World No . 1 Serena Williams will play second-ranked Victoria Azarenka in a rematch of last year 's U.S. Open final on Sunday as she attempts to become the oldest winner of the New York grand slam . The American blew away the hopes of Li Na , who had been hoping to become the first Chinese player to contest the title match of the hard-court event , as she triumphed 6-0 6-3 in Friday 's second semifinal . The defending champion , who turns 32 at the end of this month , made a blistering start against Li but the fifth seed battled back in the second set -- Williams required seven match-points to reach her seventh U.S. Open final . She has won four of those , suffering defeat in 2001 and 2011 . `` I got a little nervous there at the end but I was able to close it out , '' Williams told the crowd . `` I 'm excited to be in another final . We always have really good matches . `` Vika 's a great player and she lifts her game when it counts . I think that 's what makes the difference . '' Williams has lost just four times this year -- two of those to Azarenka -- and dropped only 16 games in 12 sets on the way to the final . The Belorussian was largely untroubled in reaching her fourth grand slam final , beating Italian underdog Flavia Pennetta 6-4 6-2 in a match marred by service struggles for both players . Pennetta , ranked 83rd in the world , was playing in her first major semifinal but had a 1-1 record against Azarenka . `` It 's been a long road to the final and it 's an amazing feeling to come out here and fight for that trophy on Sunday -- I 'm definitely giving myself the best chance for my dreams here , '' said the two-time Australian Open winner , who has a 12-3 losing record against Williams . `` Today was a great match , a lot of emotions . I think the turning point was when I finally held my serve and won the first set . I stayed tough and played really well on return games and on important moments . `` Flavia 's such a great fighter , getting to every ball , so I really had to keep my focus in the match . ''
Serena Williams reaches fifth U.S. Open final , beating fifth seed Li Na . Chinese will play world No . 2 Williams in last year 's 's final . Azarenka defeats 83rd -ranked Flavia Pennetta in opening semifinal . She lost to Azarenka in last year 's title match at Flushing Meadows .