Murray hopes to take Federer's No.3 ranking

Andy Murray was a step closer on Friday to his goal of finishing the season world number three as he beat promising Bulgarian teen Grigor Dimitrov 6-4, 6-4 to reach the last four at the Thailand Open.

The 76th ranked Bulgarian who is tipped as a future star but is yet to reach an ATP semi-final, put the top seed in Bangkok through a tough 88-minute match at the Impact arena.

"There were a lot more rallies and I got some momentum on my side," said the Scot who profited from a break in each set to advance while saving three break points against his serve.

"He didn't give me many opportunities but I was able to serve well and that was a key. It's good to have a match like this."

In Bangkok, Murray is striving to go one better than the final he reached in 2005, where he lost to Roger Federer.

With this week and two more Asian tournaments on his calendar, as well as Federer's absence from the region as he rests some niggling injuries, number four Murray is hopeful he can overtake the Swiss by the end of the season.

"These weeks in Asia are an opportunity," Murray said after his match, about his aim to claim Federer's number three spot in the world rankings.

"There is not a huge margin between us (a few hundred ranking points) and it's something I'd like to do by the end of the year."

"After the US Open I set a few goals: one is to try for number three and the other is to do better at the World Tour Finals in London."

On Saturday Murray will play French third seed Gilles Simon, who knocked out Germany's Matthias Bachinger 3-6, 6-3, 6-2.

France's Gael Monfils, seeded to meet Murray in the final, returned to the court after an injury layoff to reach the last four with a 7-5, 7-6 (7/4) win over Jarkko Nieminen.

Monfils, who rested for nearly a month after exiting early at the US Open with a knee problem, set up a showdown with American surprise package Donald Young, who thumped Japan's Go Soeda 6-1, 6-2.

World number nine Monfils had a much easier time than in his opening match, where he needed three sets to beat Colombian Santiago Giraldo.

"I was away from tennis for a long time and I woke up a bit sore this morning," said the Frenchman, playing in his ninth quarter-final of 2011. "But my level felt better in this match than the first one.

"My knee feels fine but I have to be careful with it. It still needs icing and stretching," he added.

Nieminen romped into an early 3-0 lead before Monfils found his range, breaking back for 2-3 and taking the lead 4-3 with a second break, wrapping up the opening set in just under three-quarters of an hour.

The second set went to a tiebreak after the 30-year-old Finn saved a break point in the 11th game, but Monfils took control of the decider and closed the door on his first of two match points.

Monfils has won his only previous meeting with the 55th-ranked Young, beating him in 2008 in Cincinnati. The 22-year-old former American prodigy has failed to live up to his early promise.