(adds quotes, later match)
By Barry Wood
LINZ, Austria Oct 24 (Reuters) - Ana Ivanovic reached her second semi-final in two weeks by overcoming seventh seeded Italian Flavia Pennetta 6-4 6-4 at the Linz Open on Friday.
The quality of play was worthy of a final although Pennetta was let down by a serve that produced seven double-faults.
The top-seeded Serbian, who last week reached the Zurich Open semi-finals before losing to eventual champion Venus Williams, used her strong forehand to give her an edge but the match remained in the balance until the final ball.
Both players had several chances to break in the first set but it was decided by just one for 4-3 when Ivanovic forced a forehand error from the Italian.
After four breaks of serve in the first six games of the second set Ivanovic broke to lead 4-3 with a fierce crosscourt forehand winner.
Although Pennetta came within two points of recovering the break as Ivanovic served for victory, the Serbian held on to set up a clash with third-seeded Pole Agnieszka Radwanska.
"I think it was one of the best matches I've played recently," Ivanovic told reporters. "She played very well and I thought it was a very high level of tennis.
"It was very close and could have gone either way but I knew I had to stay tough each point and try to stay composed and that's what I did so well today. I was serving really good too and that helped me with some free points."
Radwanska comfortably beat fifth seed Nadia Petrova of Russia 6-3 6-2, mixing up her game well and making intelligent use of the dropshot.
While Radwanska was quick and played the angles well, Petrova struggled with her serve, hitting six double-faults and putting just half her first serves into play.
It was only in the last few games that Petrova even looked like offering a real challenge as she became more aggressive and reduced her errors. Radwanska had to fight off three break points as she served for the match.
Second-seeded Russian Vera Zvonareva also advanced, using her stronger groundstrokes to beat eighth seed Alize Cornet of France 7-5 6-1.
The win earned Zvonareva the final place in the eight-player field for the season-ending WTA Championships in Doha next month and a semi-final against French sixth seed Marion Bartoli.
The Russian always held the advantage, with Cornet saving break points in three consecutive games. The Frenchwoman then broke to lead 5-4 but dropped the next three games and the set as Zvonareva rose well to the challenge.
Once the Russian broke to lead 3-1 in the second set the contest was practically over.
For the third match in succession Bartoli had difficulty closing out a contest, dropping the second set after leading 5-1 before beating unseeded Alona Bondarenko of Ukraine 6-3 5-7 6-1.
(Editing by Ken Ferris)