WTA Finals:Maria Sharapova bt. Flavia Pennetta

Flavia Pennetta has just played the final match of her professional tennis career.

Sharapova beats Flavia Pennetta in straight sets - 7-5, 6-1 to send Agnieszka Radwanska to the semifinals at the WTA Championships.

Invincible! Maria Sharapova wins the second set 6-1 to take the match!

Pennetta commits her 3rd double fault of the match, down 4-1 to Sharapova.

And on her 2nd serve, Sharapova hits an ace! It's her 7th of the match so far.

Pennetta holds to stave off Sharapova, who's now at 3-1.

A 6th ace for Maria Sharapova, who takes the first 3 games in a row.

Sharapova holds for the first game and breaks Pennetta for the second. She leads the Italian 2-0 in the second set.

The second set is a must-win for Flavia Pennetta. If she fails to win a set, Agnieszka Radwanska will progress to the semi-finals.

Sharapova breaks! She takes the first set 7-5.

With some strong serves today, Sharapova leads Pennetta 6-5. Can she break Pennetta, or will this go to a tiebreak?

Pennetta takes it! The two are now level at 5-5 in the first set.

Sharapova took 3 games in a row to take her lead over Pennetta.

The former number 1 now takes over the lead instead. She's up 5-4, with Pennetta serving to stay in the match.

4-3 to Flavia Pennetta as Sharapova takes the game.

Down two games in the first set, 3 consecutive game points as Sharapova looks to hold serve. She's broken, and up 40-30.

Game point! And Sharapova holds to go 2-3 against Flavia Pennetta.

Pennetta is quickly consolidating her lead. She holds to take the score to 3-1 in the first set.

Sharapova holds with her first ace of the match to win the game. She's down 2-1 to Pennetta.

Pennetta, historically dominant against the Russian, closes out the first game in 3 minutes.

The Russian and the Italian have met a total of 5 times prior to today - in the 2 matches Pennetta has lost to Sharapova, she still took a set off the former World No. 1

Pennetta has beat Sharapova at the pair's last 3 meetings - most recently at Indian Wells this year.

The Italian, who won the US Open this year beating her compatriot and friend Roberta Vinci, announced her retirement at Flushing Meadows; this will be her last professional tennis tournament.

Pennetta comes in to the tournament on the back of a straight sets victory herself - over Radwanska.

Following Agnieszka Radwanska's straight sets victory over top seed Simona Halep earlier in the day, Sharapova moves to the semifinals of the tournament.