Agnieszka Radwanska of Poland returns a shot to Maria Sharapova of Russia during their women's singles match at the Sony Ericsson Open tennis tournament in Key Biscayne, Florida, March 31, 2012. [Photo/Agencies]

* Wins title without losing set in tournament

KEY BISCAYNE, Florida - Poland's Agnieszka Radwanska used her wits to defeat world number two Maria Sharapova 7-5 6-4 to win the Sony Ericsson Open final on Saturday and once again deny the Russian.

Sharapova has now lost all four finals she has featured in at the Miami tournament and all three she has played in this year.

Radwanska's victory was her second of the year following a triumph in Dubai and her ninth WTA title, arguably her most valuable one.

"I'm just very, very happy that I have been able to play my best tennis since the beginning of the year. Let's hope that I can continue," said Radwanska, who is aiming this year to push for a first grand slam title.

"I will never be able to serve like Maria but I try different things and mix it up," she added.

Maria Sharapova of Russia is seen between games against Agnieszka Radwanska of Poland during their women's singles match at the Sony Ericsson Open tennis tournament in Key Biscayne, Florida, March 31, 2012. [Photo/Agencies]

The Polish, ranked fourth in the world, won the tournament without losing a set and she showed exactly why with a classy display that left Sharapova scurrying around the court at times.

There was characteristically little emotion from Radwanska, beyond a timid half-raising of her arms, when Sharapova went long on the final point to hand her victory.

But that was typical of the businesslike and strategic way Radwanska went about beating the Russian.

In the first set, Radwanska, in control of her service game despite lacking a powerful first serve, survived break point in the fifth game but that was a rare opening for her opponent.

The set was heading to a tie-break when Sharapova, down 6-5, suddenly lost her previously solid service game.

Sharapova, sometimes overly-aggressive, produced two loose shots and then a volley into the net to leave her trailing 0-40 in the game and although the Pole wobbled with two tame returns into the net, Sharapova failed to clear the net herself to hand her opponent the set.

Agnieszka Radwanska of Poland blows a kiss after defeating Maria Sharapova of Russia in their women's singles match at the Sony Ericsson Open tennis tournament in Key Biscayne, Florida, March 31, 2012. [Photo/Agencies]

It was a similar story in the second set - both players solid on serve but Radwanska coming out on top when it mattered at the conclusion of the set.

Radwanska fought back from 0-30 down to go 6-5 up and force Sharapova to hold serve to stay in the match.

The Russian looked agitated and was let down by some reckless strokes, twice going long on returns, as the opportunistic Radwanska lured her into defeat.

"I thought she played extremely well today, was very consistent, got that extra ball back and I made that extra mistake," said Sharapova.

"She didn't give me many errors. When I had my chances at break point, I didn't take them. When she had them, she did," said the Russian.

Tomas Wiktorowski congratulates the player he coaches, Agnieszka Radwanska of Poland, after she defeated Maria Sharapova of Russia in their women's singles match at the Sony Ericsson Open tennis tournament in Key Biscayne, Florida, March 31, 2012. [Photo/Agencies]