Melbourne, Australia (AP)— Sloane Stephens wiped away tears as she thought about hanging a poster of herself on a wall in the place of her childhood hero.

The 19-year-old American seemed to be in shock, barely able to compute how she'd produced the upset of the Australian Open by beating 15-time major winner Serena Williams in the quarterfinals Wednesday. It was her first trip that far in seven Grand Slam tournaments.  
A poster of Williams had adorned the wall on Stephens' bedroom as a child. Now, in her view, they're peers.  
"This is so crazy,'' Stephens said in a post-match TV interview after rallying from a set and a break down against an injured and angry Williams. "Oh my goodness. I think I'll put a poster of myself (up) now.''  
The 29th-seeded Stephens won 3-6, 7-5, 6-4. She calmed the nerves and started swinging harder and lifting her tempo at 4-3 in the second.  
That's when Williams jarred her back trying to pull up before the net as she chased down a drop shot. Williams let out a loud scream and hopped away. Stephens had a look back over the net, seemingly in concern.  
Williams started taking time between points, limping, and trying to stay in the shade at the back of the court.  
Williams later called for the trainer between games. She had a three-minute medical timeout and came back serving at a pace well below her usual speed.  
``Well, at that point you just have to pretend like nothing's wrong,'' Williams said. ``You think of worst case scenarios. You know, I just thought, Ok, just pretend nothing's wrong and just try your best.''  
Stephen's surprise win did instant wonders for her celebrity.  
Before the match, Stephens said she had about 17,000 followers on Twitter. A few hours after reaching her first Grand Slam semifinal, she had more than 40,000.  
And she sounded like an excited schoolgirl as she gushed about receiving a congratulatory tweet from American singer John Legend.  
``I want John Legend to sing at my wedding!'' she said. ``I was like, `Oh my God. He tweeted me. What can I do?'''  
She re-tweeted the sentiments from Legend: ``Just found out her dad is John Stephens from the Pats. (that's my real name) I had his football card when I was a kid. I was so proud, ha ha.''  
Stephens' father, former New England Patriots player, died in 2009.  
Retired basketball star Shaquille O'Neal sent a message that read: ``When u defeat a legend you become a legend.'' The Dallas Mavericks' Dirk Nowitzki wrote, ``Wow. What a win for Sloane. Some amazing defense. She gets every ball back.''  
Stephens checked her phone during her post-match news conference and said there were 213 text messages waiting for her.  
Like many a teenager, her first concern was about how high her phone bill might be.  
``I thought it was free to receive text messages, but someone told me otherwise,'' she said.  
Her mother ``is going to be like, `The money you were going to buy yourself something nice with, you're going to pay your phone bill.'''  
She's set for her biggest payday, regardless of the result in Thursday's semifinal against defending champion Victoria Azarenka, who beat two-time major winner Svetlana Kuznetsova 7-5, 6-1 in the previous match in Rod Laver Arena.  
The semifinal losers earn $525,000, double what the quarterfinal losers receive. For Williams, there's a further $1,500 deduction after she was fined for racket abuse.  
Stephens had practiced with Williams for the Fed Cup, but had played her only once, a straight sets loss at the Brisbane International earlier this month.  
``Brisbane helped me because I got the first time we played out of the way,'' she said. ``First time is always tough. Definitely I was glad that I got it there ... it helped me raise my level.''  
She'll need to maintain that level within 24 hours to play the top-ranked Azarenka on Thursday. That will follow the semifinal between No. 2-ranked Maria Sharapova and No. 6 Li Na, the 2011 French Open champion.  
The makeup of the men's semifinals was as expected, although all but one of the four players had some difficulties getting there.  
Top-ranked Novak Djokovic will continue his bid for a third consecutive Australian title Thursday when he takes on No. 4 David Ferrer. No. 2 Roger Federer and No. 3 Andy Murray will meet Friday.  
Djokovic had to get through a five-hour five-setter against No. 15 Stanislas Wawrinka in the fourth round. Ferrer had trouble in his quarterfinal against fellow Spaniard Nicolas Almagro, who served for the match in the third and fourth sets before losing in five.  
Federer, a 17-time Grand Slam champion, hadn't dropped serve in the tournament until the first set against 2008 finalist Jo-Wilfried Tsonga on Wednesday. He ended up with a struggle on his hands before advancing to his 10th consecutive Australian Open semifinal with a 7-6 (4), 4-6, 7-6 (4), 3-6, 6-3 win in 3 hours, 34 minutes.  
``I thought he played very aggressive,'' Federer said. ``I love those four-set or five-set thrillers, and I was part of one tonight.''  
Murray beat Jeremy Chardy of France 6-4, 6-1, 6-2 earlier Wednesday and hasn't dropped a set this tournament.  
Stephens' previous best run at a major tournament was at last year's French Open, where she was the first American teenager to reach the fourth round since Williams in 2001.  
She was the youngest player in the year-end top 50 despite missing the last six weeks of the season with an abdominal injury.  
``I took a lot of time off just kind of being a normal kid, doing whatever,'' she said.  
That means shopping, social networking and other things teens do.  
Stephens was under real pressure early, and it showed. She double-faulted to give Williams triple break point in the eighth game, but could save only two. Williams started pumping her fist and yelling, ``Come On.''  
Williams broke her serve again in the opening game of the second set.  
``From then on, I got aggressive, started coming to the net more and just got a lot more comfortable,'' Stephens said.  
That paid off when she broke back in the fourth game.  
Williams had injured her ankle in her first-round win, and the back injury compounded her problems in what she said later was her worst major tournament in a long time.  
The five-time Australian champion shanked a forehand to fall behind 2-1 in the third, then smashed her racket into the court, twice, flinging it toward the courtside chairs.  
She picked up her service speed and was called for a foot fault, further annoying her.  
Williams got the first break of the set and seemed to be back on track for victory, but Stephens answered immediately.  
Serving to stay in the match, Williams hit an attempted passing shot long and looked up to the sky, muttering to herself.  
She hit backhands into the net on the next two points, and her winning streak had ended.  
Williams walked around the net post to shake Stephens' hand. The quick turnaround between matches makes it difficult for Stephens' family to make it to Australia for her semifinal.  
``I'm kind of upset my mom's not here, and my brother,'' she said. ``I know definitely everyone's watching back home and is very proud of me, so (I'll) just do my best and make them happy.''