Key Biscayne, April 2:

For 90 minutes Svetlana Kuznetsova kept Maria Sharapova on the run, dashing from corner to corner in vain pursuit of a championship.

As a weary Sharapova found herself on the verge of defeat, she went scrambling yet again after a shot and exclaimed, “Ai-yi-yi.” The crowd laughed, and Kuznetsova won the exchange to reach match point. The former US Open champion then finished with an ace for her first title in 18 months, beating Sharapova 6-4, 6-3 at the Nasdaq-100 Open.

Seeded 12th, she won the all-Russian final thanks to a superior serve and forehand, repeatedly driving Sharapova into one corner and then hitting a winner into the other.

The No 4-seeded Sharapova finished as runner-up at Key Biscayne for the second year in a row. She said she was “a little tired” after winning 11 consecutive matches this month, including Indian Wells final.

Kuznetsova broke serve to go up 3-1 in the opening set and led the rest of the way. As Sharapova fell behind, a small plane with an advertising banner hovered over the stadium, compounding her unhappiness. She gestured in annoyance at least twice and complained to the chair umpire about the noisy plane.

The county, which owns the tennis complex, worked with the Federal Aviation Administration to resolve the matter, and the plane departed after the first set.

Replay didn’t help Sharapova, either. All 11 of her challenges were rejected, and Kuznetsova won her only challenge in the final.

Fans will have another underdog to cheer for in men’s final: No 6-seeded Ivan Ljubicic of Croatia, playing his first final in the United States at age 27. He’ll face top-seeded Roger Federer, the defending champion.