INDIANAPOLIS, Indiana (AFP) - James Blake tightened up his game in dramatic fashion Friday, hammering of Taiwan's Lu Yen-Hsun 6-2, 6-0 in 45 minutes for a semi-final spot at the Indianapolis Tennis Championships.

After struggling a day earlier to put away 293rd-ranked Korean qualifier Jun Woong-Sun, the 2006 champion and world number eight Blake was desperate to lift his level.

The top seed did so in impressive style in the shortest match of the tournament to line up a clash with defending champion Dmitry Tursunov.

The Russian completed the first-ever move of all top four seeds into the semis of this event with a 3-6, 6-3, 6-1 defeat of Chilean Paul Capdeville.

"I felt great, this was my best match of the tournament," said Blake, winner of 10 of his last 11 Indianapolis matches. "It's exciting to get back on hardcourt.

"This is the part of the season where I play my best. I was playing too much to the score yesterday and not the opponent.

"Today I didn't want to look up when I led 6-2, 3-0, I just wanted to concentrate on playing well, I wanted to play my best."

Blake notched seven aces, never faced a break point and broke his Asian opponent five times as he improve to 34-15 on the season.

Frenchman Gilles Simon preyed on the frustrations of Tommy Haas in a 4-6, 6-4, 6-2 defeat of the German.

Simon, who won his third career ATP title in Casablanca last May, next faces the huge serve of American fourth seed Sam Querrey, who hammered 17 aces as he beat compatriot Bobby Reynolds 6-1, 3-6, 6-3.

Haas, seeded fifth, won the opening set in steamy temperatures but lost his way in the second as he went down a break in the ninth game, 4-5.

After dropping the second, the former number two was handed a rare point penalty for the most innocuous of offences - a racket smash and a minor swear - by umpire Fergus Murphy in the second game of the third.

That incident appeared to break Haas's will and opened the door for Simon, now one victory away from becoming the first French finalist here since Olivier Delaitre in 1994.

"I could tell Tommy was getting frustrated and I tried from the second set to hit the ball harder. I feel my game is coming along," said the 25th-ranked Simon, 24-16 in 2008.

Haas admitted his emotions rose to the surface at the wrong moment.

"My confidence and motivation suffered when I got broken back. I was struggling to finish points and lost come focus on my technique."

Querrey, 20, claimed his debut title last March in Las Vegas and improved to 22-15 this season with his win over Reynolds, who was the last American standing at Wimbledon this month.