WTA Finals: S. Williams d. Wozniacki (VIDEO)

SINGAPORE—Caroline Wozniacki was right there, at a least for a second. The Dane was up 4-1 in the third set, screaming, pumping, ready to upend Serena Williams for just the second time. The 18-time Grand Slam champion rarely gets nervous, but it wasn't the same story for her good friend Wozniacki, who stepped backward at crunch time. She was oh-so close, but could not cross the finish line.

Wozniacki fought off three match points, but she hesitated just enough for Serena to snare another win, this time 2-6, 6-3, 7-6 (6).

Williams started the match extremely flat, so flat that she annihilated her racket down 5-2 in the first set.

In her second match this week, against Simona Halep, Williams lost 6-0, 6-2, saying she was totally out of it and couldn't find her legs. Wozniacki’s start was similar to Halep’s—she was flying during the first set, moving quickly and confusing her opponent. But Williams took a deep breath in the second set, finding her forehand and, finally, nailed her huge serves. The 33-year-old began to kiss the lines, hitting around 120 M.P.H. in the corners.

Williams, who entered the match 9-1 against Wozniacki, was churning, going down the lines with hard forehands and backhands. Wozniacki may be as fast as a rabbit, but there is no one who can catch up Williams if she is hitting the chalk.

But the third set was much more complicated. As Williams said later, she was pretty surprised at how Wozniacki has changed her approach. Not only was the former No. 1 standing inside the baseline, but she also was willing to use her forehand down the line more effectively (Wozniacki still needs to improve her cross-court forehand) and jumped on Williams’ second serve. She also went for bigger serves and kept trying to push Williams out wide.

The crowd became louder and louder, so loud that Williams and Wozniacki both screamed at 2-2, after Serena fought off a break point at 30-40 by diving at the net, while Wozniacki couldn't dig out another pass. The two went into a see-saw battle nearly every point.

Down 15-30 at 3-3, Serena boomed a gigantic delivery, then another, and rushed the net to put away the ball perfectly. At 4-4, Wozniacki passed a rushing Williams with a gorgeous backhand. She broke her that game, but didn’t go for her serves with a chance to end the match. On the contrary, Williams smoked three huge forehands to break to 5-5 and stay alive.

Wozniacki was right there, swinging away until she hesitated. Holding a break point, the 24-year-old rushed in the middle of the court, leapt up, and had a backhand that she could have crushed down the line—but it clipped into the net and fell backwards. Williams would hold to 6-5, courtesy of a 123 M.P.H. ace and then a 121 M.P.H. bomb that Wozniacki could barely touch.

Serena thought she was ready to finally defeat Wozniacki and give her buddy a big hug. But not yet. The American lost a match point, after Wozniacki came into the net, bent very deep, and knocked back three swings to put it away. Williams grew upset and a little bit rattled.

In the deciding tiebreaker, Wozniacki went up 4-1 after four Williams errors. But then Serena got a little lucky, when she hit a ball that went on the top of the net and dribbled over, just enough so Wozniacki couldn't rush up to it and touch it. Williams apologized, but Wozniacki was able to walk on changeover and calm down.

Then Wozniacki stepped back, just as she ended to step forward. She pushed her serves instead of attacking. She floated a backhand slice and Williams crushed it to 3-4. Williams then bashed a sweet serve to 4-4 and a massive forehand to 5-4. Wozniacki then came into the net, but could not handle the ball and went to 6-4. Two match points.

It was Serena’s turn to stumble, missing a backhand and then a forehand. But her serve came to the rescue just in time. Earning her fourth match point with it, Serena then sent Wozniacki to her right, for a fairly easy forehand. But she pushed the ball well out to her right to end the match.

Wozniacki played an exceptional tournament this week, winning her first three matches and positioned to upset Williams, but she couldn't reach the final.

“This really sucks.” Wozniacki said. “You know, being so close and still losing, it really sucks.”

Williams was very pleased with the win and says that she wants to play substantially better against Simona Halep in the final, especially considering the score of their last match. For this day, though, she was just happy that she could figure out her friend in time.

“She was playing me different than she had in the last four or five times we played this year, so I just had to adjust to that,” Williams said. “I thought she was playing totally different. She had a whole new strategy…it clicked today. I thought, ‘Ha! I got you now.’”