Murray is close to breaking into the world's top 10

The Briton, who beat Pless on his way to the San Jose title last week, won 6-3 7-6 (7-4) and next faces Stefan Koubek in the last eight.

Murray broke in game eight but needed a tie-break to win a tighter second set.

A win over Koubek could lead to another semi-final showdown with Andy Roddick, who beat Benjamin Becker 7-6 6-4.

Murray beat America's Roddick in the last four of last week's SAP Open before going on to claim his second ATP Tour title.

I didn't serve that consistently but when my first serve went in I won 90% of the points Andy Murray

Against Pless, Murray failed to convert two break points in the second game but made no mistake when leading 4-3 and served out the set.

Pless held his own on the second set, although Murray let several break points slip away, but the Scot raced into a 6-2 lead in the tie-break and converted his third match point.

"I thought I hit the ball much better today," Murray said.

"I didn't serve that consistently but when my first serve went in I won 90% of the points.

606 DEBATE: Comment on Murray's recent form

"Maybe I need to play a little more aggressively on break points. I've been putting the return in play but not really following it up."

Top seed Roddick hit 14 aces to beat Becker and will now play Yen-Hsun Lu of Taipei.

Roddick said: "He served just as big as I did. I thought I outplayed him from the baseline for the most part.

"I started hitting my forehand better in the tie-breaker and through the second set and that was probably the difference."

Among Thursday's other winners were second seed Tommy Haas, who beat American Amer Delic 7-6 (7-2) 7-6 (7-5) to reach the last eight.

Number four seed Mardy Fish also progressed thanks to a 6-1 7-6 (11-9) victory over Juan Martin Del Potro.