Top seed Tomas Berdych needed 20 aces to hold off eager challenger Lu Yen-Hsun of Taiwan, 7-6 6-4 on Friday to reach the semi-finals of the Thailand Open.

The world number six Czech who led his nation into a second straight Davis Cup final next month, will Saturday play French fourth seed and 2009 champion Gilles Simon, who took treatment for a back problem during his 6-4 5-7 6-4 win against Igor Sijsling.

Simon came to Thailand after winning the Metz title last weekend and has been scheduled for noon matches for the past two days.

He had to have on-court treatment for back pain but hopes to recover enough to take on Berdych, whom he leads 5-2 in their career series.

“I’ll just take treatment and hope to be fit for Saturday, I have to be 100 per cent if I want to win,” said the ATP number 14.

“I felt pain in the second game of match, it got better, then I felt it again later, But (after treatment) it started to feel better, so I just played on, My back is not in a great shape now. The injury is a bit of everything.”

Simon won in just under two and a half hours, fighting off a dozen aces from Sijsling and saving 14 of the 16 break points.

Berdych is seeking his first title since last October and stands as the only member of the ATP top 10 without a 2013 trophy,

He said he had a workout against Lu, taking more than an hour to win the first set after coming form a break down.

“I usually do the attacking, but today I was second best. He made plenty of winners and played aggressive. I had to wait for him to make errors, which is not my style, I needed to adjust to his game today, but I did.

“It was a tough match and I’m happy to go through. He played well, it proves how tough tennis is these days.”