When she won the U.S. Open last year, Kim Clijsters at last seemed on the verge of big things.

The 23-year-old Belgian had finally freed herself of the nagging questions about her ability to win a major title. Her left wrist, once so fragile that she feared it would spell the end of her career, had held up nicely through a grueling summer hard-court season in which she posted a 23–1 record with four titles, including the Open. Her personal life was back in order, too, after the end of her relationship with Lleyton Hewitt and the beginning of a better one with Brian Lynch, a former NCAA basketball player now playing pro ball in Belgium (the couple are engaged).

A happy, healthy Clijsters seemed a good bet to take at least a few more Grand Slam titles, even if she wanted to retire after two more seasons to have children and get on with the rest of her life. She got off to a fine start in Australia this year despite back and hip ailments, before suffering a serious ankle injury that forced her to retire against eventual champion Amelie Mauresmo in the semifinals.

Clijsters has not been the same since, or at least until this week, when she at times flashed her old form in defending her title at the Bank of West Classic at Stanford University against Patty Schnyder in a less-than-compelling final, 6–4, 6–2. Clijsters’s record now stands at 32–8 with two titles.It’s off her pace from last year (67–9, nine titles), but there’s time, and based on her performance this week, hope. Come September, the Belgian may yet hoist the U.S. Open trophy again, and perhaps add another $1 million bonus to her bank account if she wins the U.S. Open Series for a second consecutive year.

There is no evidence of any lingering physical effects from Clijsters’s ankle turn against Amelie Mauresmo. Yet there is at least anecdotal evidence that Clijsters has changed her tactics since returning from that injury.

At the French Open, ESPN commentator Brad Gilbert suggested that Clijsters had started taking more risks on her groundstrokes, looking for winners rather than chances to lengthen points and frustrate her opponents. Clijsters agreed in an interview, suggesting that it might be better for her longevity if she could learn to end points more quickly.

If Clijsters is looking to end more points, perhaps she has too often crossed the line between aggression and impatience. At her core, the Belgian remains the sort of player who infuriates opponents and causes them to commit errors, while making the most of her opportunities to hit winners when they arise.In tennis, frustration builds gradually, and if Clijsters is unwilling to annoy her opponent point after point, she can begin to look listless. The contest that most comes to mind was her defeat at the hands of Justine Henin-Hardenne in the French Open semifinals. Clijsters declined to scrap and claw her way into the match.

That said, Clijsters’s performance in California this week offered some encouraging signs.Against 17-year-old slugger Nicole Vaidisova in the semifinals, Clijsters fell behind by a break of serve before patiently waiting for the aggressive — and error-prone — Czech to misfire. Leading 4–2 in the first set, the teenager double faulted three times.Just as important, however, was the cross-court slice backhand Clijsters hit at deuce, as Vaidisova debated moving to the net. The ball stayed low, and the indecisive Vaidisova eventually flubbed a backhand drop shot as she fell to one knee.Clijsters took a big risk two games later, serving a slice ace on a second serve at set point for Vaidisova. She broke again with a fine service return and a patient rally that ended in a Vaidisova error.

Yesterday, Clijsters did not need to do much more than play steady. Schnyder looked sluggish after having defeated Tatiana Golovin Saturday evening. She repeatedly made poor decisions and horrible mistakes, including a drop shot attempt from 10 feet behind the baseline and a short forehand that should have been a cross-court winner but instead ended as an error down the line. In the point of the match — indeed, perhaps the only good point of the afternoon — Schnyder took control of a long rally, moving Clijsters off the court to her backhand side. The Belgian sliced another fine defensive backhand, and then easily retrieved a Schnyder drop shot and converted it into a backhand down the line winner. Clijsters finished the match with an ace.

At the Acura Classic this week, Clijsters again will play the role of favorite, and another title would put her well on her way to dominating the hard court summer. Venus Williams has dropped out of next week’s event (wrist), as has wild card entry Serena Williams (her knee again), and Lindsay Davenport (injured back). (All three of those women are scheduled to appear in Los Angeles the week after next.) Mauresmo and Henin-Hardenne, the two best players in the world at the moment, are not scheduled to return to action until the Rogers Cup in Toronto, which begins August 14.

Clijsters probably won’t mind having some time alone on the hard courts, on which she moves better than anyone in the women’s game. If she continues to round into form, the U.S. Open ought to be her tournament to win.

***

After an all-American final in Indianapolis last week, the America took a leave of absence from the final weekend of the Countrywide Classic in Los Angeles.

Andre Agassi’s recurring back injury responded well to a cortisone shot, but the 36-year-old American took his final bows in the quarterfinals after losing a three-set match to Fernando Gonzalez. Andy Roddick, accompanied by new coach Jimmy Connors, had to forfeit his quarterfinal match because of a back strain. One finalist, Dmitry Tursunov of Russian, is almost American (he has lived in California since age 12).

The home favorite fell short, however, losing to Tommy Haas, 4-6, 7-5, 6-3.

tperrotta@nysun.com