Her eyes locked on the target, Serena Williams tossed the ball into the air and in a blur of explosive motion launched a 24th ace to end the brave resistance of Victoria Azarenka and reach her seventh Wimbledon singles final on Thursday.

In doing so the 30-year-old became the oldest woman to reach the final since Steffi Graf in 1999 and now only Poland's Agnieszka Radwanska, who beat Germany's Angelique Kerber 6-3 6-4, stands between her and a fifth All-England Club title.

Serena Williams of the US celebrates after defeating Victoria Azarenka of Belarus in their women's semi-final tennis match at the Wimbledon tennis championships in London, July 5, 2012. [Photo/Agencies]

The 15,000 fans packed into a sunny Center Court gasped in awe as each Williams thunderbolt flew past the Belarussian.

To her credit Australian Open champion Azarenka stood firm in the face of the incoming fire and she would have earned plenty of new admirers in a 6-3 7-6 defeat.

The 22-year-old second seed even had the temerity to break the Williams serve midway through the second set as she dragged the contest into a tiebreak, but she was finally overwhelmed.

Since Williams won the last of her 13 Grand Slam singles titles at Wimbledon in 2010 she fell into a pit of despair after a gashed foot and subsequent health problems threatened to end a golden career.

Even the often controversial American's harshest critics would readily concede they are pleased she is back, still hungry for titles and still swaying on Center Court's hallowed turf.

Those trying to avoid actual bodily harm trying to return her serve may not agree, but Wimbledon would be poorer without her.

After some patchy performances in the early rounds, Williams changed gear against defending champion Petra Kvitova in the quarterfinals and during a clinical first set against Azarenka, she was virtually unplayable.

She began the third game with three consecutive aces before Azarenka somehow got her racket to the fourth. The game took barely a minute to complete.

Victoria Azarenka of Belarus reacts during her women's semi-final tennis match against Serena Williams of the US at the Wimbledon tennis championships in London July 5, 2012. [Photo/Agencies]

Azarenka, who caused chuckles from the crowd with her droning sound effects, dug deep from a break down in the second set and pierced Serena's armour to level the match at 3-3.

Showing tremendous fight she saved three break points in the next game and for the first time Williams looked ruffled.

Killer blow

Williams edged ahead in the tiebreak with her 23rd ace, to equal her Wimbledon record and despite wasting a match point with a lob that sailed out, she made no mistake on the second, as her trusty serve supplied the killer blow.

"I've been working so hard, I really wanted it," Williams, who jumped for joy, said. "She was playing well and I got a little tight in the second set. I was looking too far in the future. I was just getting excited that I was so close, but I can't do that. I was happy to get through that second set tie-break."

Radwanska, who not only will contest her first Grand Slam final on Saturday but could also claim the No 1 ranking if she wins, may want to avoid watching a Williams DVD before bedtime as she prepares for the biggest day of her career.

The former Wimbledon junior champion, who has become the first Pole to reach a Grand Slam final since Jadwiga Jedrzejowska at the French Open in 1939, is not known for a power game, more the accuracy and intelligence that proved too much for Germany's Kerber.

The third seed slipped 3-1 behind in a nervy start to her first Grand Slam semi-final but soon had Kerber on the run with her superior courtcraft.

After sealing the first set with an ace, Radwanska broke again early in the second and never remotely looked like relinquishing her lead.

"I'm the first (Polish) player to win in a semifinal for many years, so I think this is already a big success," Radwanska, who lifted the junior title in 2005, said.

"And now here in the final, it's even bigger. This tournament is already one of the big part of tennis history in Poland. I'm happy to be part of that."

Serena Williams of the US celebrates after defeating Victoria Azarenka of Belarus in their women's semi-final tennis match at the Wimbledon tennis championships in London, July 5, 2012. [Photo/Agencies]

Another player with his eye on history is Briton's Andy Murray who on Friday will start as favorite to beat Frenchman Jo-Wilfried Tsonga in the second of two juicy men's semis.

Murray mania is expected to grip the nation on Friday, when thousands of fans are expected to flock to the grounds just to watch Murray's bid to become the first British man to reach the Wimbledon singles final since Bunny Austin in 1938.

Should Murray win he would face either defending champion Novak Djokovic or six-times winner Roger Federer in the final.