Intro:

Serena Williams, Li Na, Maria Sharapova and Angelique Kerber reach the final four of the WTA Tour's Rome Masters on Friday.

Script:

Ninth seed Serena Williams faced Flavia Pennetta in the quarter-finals of the Rome Masters on Friday. 

Pennetta seemed to be hampered by a wrist injury from the outset and had treatment on court when she was trailing 3-0.

The Italian retired in the end, trailing 0-4, 0:40, for Williams to book her place in the final four.


Eighth seed and defending French Open Champion Na Li faced 14th seed Dominika Cibulkova in the second quarter final.

The Chinese player opened up a 4-0 first set lead before taking it 6-1.

Victory seemed in sight but the Slovakian fought back and reeled off four straight games to take the second set into a tie break. But Li took a 6-1, 7-6 (7-4) win to set up a semi-final with Serena Williams. 

Defending champion Maria Sharapova took on Venus Williams in a battle of the big-hitters. 

Sharapova whipped a backhand cross-court to set up a break point in the ninth game and took the first set 6-4. 

The second seed continued to dominate as the second set got underway and closed out a valuable 6-4, 6-3 win.

Sharapova will next face Germany's Angelique Kerber, after the number twelve seed put out Wimbledon champion and Australian Open semi-finalist Petra Kvitova 7-6(2), 1-6, 6-1.

After two and-a-quarter hours on court, Kerber closed out her sixth victory in her last ten matches against Top 10 opposition - the German will now move into the top ten in the rankings herself as a result. 

Sharapova and Kerber are tied in their head-to-head series at 1-1, with both meetings coming this year.