KEY BISCAYNE, Fla. - Maria Sharapova was confused and Caroline Wozniacki was mad. The linesman was wrong and the chair umpire was right.

Sharapova won the disputed final point after an overrule by the umpire, edging Wozniacki 4-6, 6-2, 6-4 Thursday in the semifinals at the Sony Ericsson Open.

"Obviously you don't want it to end that way," said Sharapova, who will meet Agnieszka Radwanska in Saturday's final.

At 40-30 in the last game, Sharapova hit a second serve that the linesman called long, which would have been a double-fault, but umpire Kader Nouni immediately reversed the ruling and ordered the point replayed. The call couldn't be reviewed because Wozniacki had no challenges left, although TV replays showed Nouni was correct to overrule.

Sharapova was awarded two serves and took advantage with a big first serve to set up an overhead slam for the victory.

Wozniacki, angry about the overrule, declined to shake Nouni's hand and had words with him as she walked to the exit.

"It was a pretty crucial point," she said. "When the ball is so close, I think he should give her a chance to challenge, at least when I don't have any challenges."

Sharapova said she didn't realize Wozniacki had no challenges left, and added she would have challenged the call herself had it not been overruled.

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"It's obviously a tough situation to be in," Sharapova said, "because it's so close to the end of the match, and both of us had fought so hard for over two hours."

Top-ranked Novak Djokovic advanced to the men's semifinals without argument, beating No. 5 David Ferrer 6-2, 7-6 (1). Djokovic lost a remarkable 40-shot rally that had spectators gasping as it progressed, but he played a nearly flawless tiebreaker to seal the victory.

"Coming into this tournament, I was confident," Djokovic said. "And I feel that I am playing better and better as the tournament goes on."

Djokovic seeks his third Key Biscayne title and second in a row. His opponent Friday night will be No. 21 Juan Monaco, who advanced on his 28th birthday by eliminating the last American in either singles draw, No. 8 Mardy Fish. The scrappy Monaco dominated from the baseline and hit only eight second serves during the 6-1, 6-3 victory.

"This is the way to celebrate my birthday, playing like this," Monaco said. "I feel proud and very happy."

No. 2 Rafael Nadal, seeking his first Key Biscayne title, plays 2009 champion Andy Murray in the other semifinal.

Radwanska's progress toward her first Key Biscayne final was interrupted briefly in the second set by a power outage that caused a delay of 20 minutes. She then closed out a 6-4, 6-2 victory over Marion Bartoli, who hurt her left thigh in the early going and limped through the rest of the match.

"You're really focused on the match, and I really wanted to finish in two sets," Radwanska said. "Suddenly the lights go off. It was kind of weird."

The No. 5-seeded Radwanska is 0-4 this year against top-ranked Victoria Azarenka and 25-0 against everyone else.

Sharapova, seeded second, improved to 4-0 in Key Biscayne semifinals. She's 0-3 in finals at the event, losing every set.

"I'm happy that I gave myself another chance to go out there and try to change that," said Sharapova, who attended the tournament several times as a fan when she was a youngster training in Florida.

Sharapova will play in her second successive final and third this year. She was runner-up at the Australian Open in January and at Indian Wells two weeks ago.

Wozniacki, a former No. 1 now ranked sixth, fell to 1-7 lifetime against opponents ranked in the top two.

Sharapova was in an attacking mode against the Dane, a relentless retriever whose defense helped her beat Serena Williams in the quarterfinals.

Sharapova went for winners at every opportunity and hit 55, but she also committed 46 unforced errors. Wozniacki totaled only 13 winners and 25 errors.

"Being aggressive is really the key," Sharapova said. "If you let her play many, many balls, she's such a great mover around the court and she can be out here for many hours, and that's not really my game."

Sharapova was a point away from a 5-1 lead in the opening set but then began overhitting her forehand, which allowed Wozniacki to sweep five consecutive games and take the set.

Shrieking with each shot, Sharapova regained her accuracy thereafter. By the time she led 4-love in the second set, she had a 27-4 advantage in winners.

She went ahead 5-2 in the final set before Wozniacki staged one last rally, which fell short amid the fuss at the finish.

"Maria started off really well and played aggressively," Wozniacki said. "She played some good tennis out there. I tried to do my best, and it just wasn't enough."

Sharapova improved to 17-1 in three-set matches since the beginning of 2011.