Shahar Peer has risen to 20 in the world rankings after her best-ever performance in a major tournament last week.

Despite stifling security measures to protect her, Peer reached the semi-finals of the Barclays Dubai Championships, one of the biggest non-grand slam tournaments, with victories that included top seed Caroline Wozniacki, world No. 10 Li Na and No. 15 Yanina Wickmayer, before succumbing to eventual tournament winner Venus Williams. She had gone into the tournament without a victory over a top 20 player since last March.

Peer, who was excluded from the tournament last year because she is Israeli, was subject to the tightest of security. The timing was unfortunate as details emerged of the assassination of a Hamas official in Dubai allegedly by a Mossad hit squad. Peer was only allowed to leave her hotel immediately before games and returned straight after the game was completed. All her matches, including the semi-final with Venus Williams, were played on a small side court and she was not allowed to give press conferences. She was given an entire floor of a hotel, which she shared with her father Dov, a South African born high-tech executive.

Peer said: "I had a lot of peace and quiet and spent much of the week surfing the internet in my room. My bodyguards were great – all 25 of them. But I played my best ever tennis so maybe I should try re-creating such conditions again."

Peer has not been in the top 20 since June 2008, and last August she had slumped as low 68. After the excitement of Dubai she withdrew from this week's tournament in Monterrey and will return to action at Indian Wells on March 8. Her next target is to surpass her career high ranking of 15.