NEW YORK — So expressionless and serious-minded all night, Venus Williams waited to crack a smile until her victory was complete.That’s when Williams simply could not help but grin — as she walked to the net for a handshake, as she waved to the crowd, as she spoke about reaching her first U.S. Open semifinal since 2002.And, certainly, as she thought about getting a crack at the player who eliminated her sister.Way down Wednesday night, Williams turned her game on when she needed to and was stronger down the stretch, beating No. 3-seeded Jelena Jankovic 4-6, 6-1, 7-6 (4) in the U.S. Open quarterfinals.Next up is a semifinal against No. 1 Justine Henin. Know this: Venus Williams watched Henin beat Serena Williams on Tuesday and wants to right the wrong.“I wasn’t happy with that result at all. I was sad that she lost. I didn’t like to see her so upset,” Venus said. “I definitely have to try to win for Williams.”The other semifinal has 2004 Open champion Svetlana Kuznetsova against No. 6 Anna Chakvetadze in a matchup between Russians.Against Jankovic, the older Williams took a while to find the mark, falling behind by a set and a break. But by the end she was playing as well as she did en route to winning Wimbledon in July for her sixth Grand Slam title.Jankovic made four bad mistakes to allow Williams to take control in the decisive tiebreaker.“We had some long points, and I was the one making the errors. I maybe was a little bit excited,” Jankovic said. “I thought that it will go in, but it didn’t.”The 12th-seeded Williams ended it with a swinging forehand volley, an appropriate conclusion given that she made 55 trips to the net, winning 39 of those points. Jankovic was far less aggressive, pushing forward only six times.Williams dictated play in general, finishing with a whopping 60-17 edge in winners, and after the last one, her face muscles finally relaxed with joy.“I like to laugh after the match, especially if I won,” she said. “I try to stay focused, in the zone.”Speaking to the spectators afterward, Jankovic said: “First of all, I want to say, ‘Well done,’ to Venus. She deserved to win. She was better at the end.”That was quite a different take on things from a disappointed loser than Serena Williams offered after her straight-set setback against Henin, including a reference to the Belgian’s “lucky shots.”Now take that in, and consider Jankovic’s explanation for why she applauded a couple of Venus Williams’ top efforts and smiled in appreciation when she glanced at the speed readout and saw a 121 mph serve.“When she hits a great shot, why not? You can say, ‘Well done.’ Nothing wrong with that,” said Jankovic, who beat the older Williams at Wimbledon last year and at the French Open this year. “I cannot do anything when she hits an unbelievable serve. I cannot return it. So why not give her credit?”Jankovic enjoyed nearly every moment out there, smiling while waiting to receive serves and laughing even when she shanked a ball off her ankle or, later, when she slipped to the ground and did a full splits on a key third-set point.She broke in the very first game, capping it with a perfectly placed lob. That was the first of four lob winners that Jankovic curled like a rainbow over the 6-foot-1 Williams, including one so good it drew applause from the American’s mom.Jankovic broke again for a 4-1 edge by smacking a return winner off a 100 mph serve. Then, serving for the opening set at 5-4, Jankovic fell behind love-30 and easily could have folded, much as she did when she blew a huge lead against Henin in last year’s Open semifinals.But this time, she hung tough, taking four points in a row — including ending one 19-stroke exchange with a backhand winner — to grab the set. That drew loud chants of “Yell-eh-na!” from Serb supporters standing at the top of the upper deck.The second set started with more of the same. Williams hit two double-faults — she wound up with eight — and wildly missed a swinging volley to set up another break point. Jankovic converted it with — what else? — a lob, then held up a fist.And right there is where Williams flipped a switch, her game suddenly as bright as all of the flash bulbs popping around Arthur Ashe Stadium. She took seven of the next eight points, opening a six-game sweep through the end of the set.The third set featured some brilliant shotmaking by both women, exactly the sort of display tournament organizers envisioned when they moved this match off Tuesday’s schedule in hopes of adding some star power Wednesday.That sure worked, and the enthralled fans showed their appreciation with a standing ovation before the tiebreaker. They repeated the gesture when the match ended.“It went the distance,” Williams said. “It was awesome.”When they were done, it was time for the day’s most anticipated encounter: No. 1 Roger Federer against No. 5 Andy Roddick in a quarterfinal that was a rematch of last year’s final.In Wednesday’s earlier men’s quarterfinal, Nikolay Davydenko hardly appeared to be a man with a lot on his mind.He’s at the center of tennis’ betting probe, well aware that he’ll be sitting down with investigators in the coming weeks. He’s also on quite a run at the U.S. Open, well aware that he’ll be a big underdog against his next opponent.The No. 4-seeded Davydenko reached the semifinals at Flushing Meadows for the second consecutive year by beating No. 10 Tommy Haas 6-3, 6-3, 6-4, then again denied any involvement with gamblers and offered an explanation of what he thinks led to the red flags last month.“I don’t care what’s happening out there,” Davydenko said, referring to the investigation. “For me, it’s more important what I do right now here.”A British online gambling company voided all bets on Davydenko’s match against 87th-ranked Martin Vassallo Arguello in Poland in early August, after $7 million was wagered — 10 times the usual amount. Most of the money backed Arguello, even after Davydenko won the first set; the match went to a third set, and Davydenko quit with a foot injury.His theory: Someone had inside information that he’d been hurting, and thought, “Sell all your houses and everything, you know, to win some money.”The Russian said his manager and the ATP are working to schedule a meeting with investigators.Davydenko might be able to set that aside for the moment, but he won’t be able to get around this: He never has won a match against either possible semifinal foe, going 0-9 against Federer, 0-4 against Roddick.— Associated Press writers Howard Fendrich contributed to this report from Atlanta.