Before Venus and Serena Williams were tennis icons, before they had won a total of 15 major singles titles and collected tens of millions of dollars in prize money and endorsements, Richard Williams, their father, predicted that both sisters would be great, but that Serena, the younger sister, would be the better of the two.

It turns out that Mr. Williams might have made the wrong call. This evening, Venus and Serena will face each other for the 17th time. Sadly, their meeting comes in the quarterfinals at the U.S. Open, far too soon for the two best players in the draw. But it might not be too early, after tonight, to discuss whether Venus, who won her fifth Wimbledon title earlier this year, will command more attention in the record books once the sisters have left this sport behind.

As Venus and Serena settle into their late 20s, it’s Venus who is aging well. She moves better, she plays with more variety, and she seems more confident than ever before. Nick Bollettieri, the famed coach who has worked with 10 players who reached the no. 1 ranking, including Venus and Serena, says he’s not surprised that Venus is on the upswing at this stage in her career.

“Serena’s game takes a lot more out of her,” Bollettieri said. “Venus’s game is a lot more graceful, more journeys to the net. Serena, she’s going to huff and puff and get two or three balls that maybe sometimes she should even let go, but it’s been pounded into her mind, ‘I’m going to get the ball.’ The question is, can that ankle or that knee take that constant pounding?”

Bollettieri also suggested that Venus likes her chances heading into this evening’s match.

“When I saw them today, Serena said, ‘This is crappy that we have to play each other,'” Bollettieri said. “Venus said, ‘I want to win.'”

Venus’s return to the spotlight — and to the role of co-favorite alongside her sister — has been many difficult years in the making. In 2002, Serena dominated the women’s tour like no one since Steffi Graf. She won three major titles and added a fourth consecutive major at the Australian Open in early 2003. No one hit the ball as hard as her, no one served as well, and no one was more intimidating. Venus was with her sister every step of the way: She played in all four of those major finals, and each time she came up short. She had gone from older sister, the one who showed Serena the ropes, to sidekick. Serena beat Venus at a fifth consecutive major, in the 2003 Wimbledon final, and then both sisters missed the rest of the season with injuries.

Venus has never said so, but her confidence must have suffered more than her body. Her drought at major tournaments would continue for the next year and a half, and by late 2004, other players seemed to have passed her by, too. Maria Sharapova stunned the women’s game by winning Wimbledon in 2004 at age 17. Dozens of other Russians arrived on the scene, and several of them — Vera Zvonareva, Elena Dementieva, and Anastasia Myskina — defeated Venus in important tournaments. Justine Henin won her first major title and her fellow Belgian Kim Clijsters showed she could match the sisters in terms of speed and athleticism.

These women denied Venus a French Open title, the only major she has yet to win. Others dealt her more dispiriting defeats: Lisa Raymond, best known as a doubles player, beat Venus in the third round at the 2004 Australian Open; Karolina Sprem won their second-round match at Wimbledon in 2004, and Lindsay Davenport pinned three consecutive losses on her American colleague in 2004. Back then, it wasn’t odd to believe that Venus might never win another major title. Everyone knew that her strokes were flawed, that her forehand would break down after a series of long rallies, that her second serve would disappear for games at a time. To beat Venus, one need only prolong the match and wait for her to self-destruct.

Then along came Wimbledon in 2005. Venus played perhaps the best tournament of her career on the lawns of the All England Club, and she has since followed it up with two more titles there, this year and last year. At last year’s U.S. Open, she played a splendid match against Henin, the eventual champion, in the semifinals. This year, she’s playing the type of tennis that many had hoped she would play in years past, an attacking game built around a strong serve, a powerful forehand, and volleys that are some of the best in the game. Venus has long arms and legs and she’s using them to her advantage better than ever before. She no longer lets her opponents dictate play and points no longer last long enough for her to make awkward errors.

“Nowadays I throw in a slice and loopers. I don’t know what’s gotten into me,” Venus said. “If I can have the opportunity to move forward, that’s how championships are won.”

Whatever has inspired Venus to play this way, let’s hope it lasts. She’s playing some of the finest, and most entertaining, tennis of her career. If she wins tonight, she’ll lead her sister 9-8 in head-to-head meetings. If she wins this tournament, she’ll tie her sister in major titles. (As of today, Serena has eight to Venus’s seven.) Only one sister can move on in this tournament and, right now, Venus looks to be the one. By this time next year, she might sprint in front of her sister for good.

Mr. Perrotta is a senior editor at Tennis magazine. He can be reached at tperrotta@ tennismagazine.com.