Brisbane - Top seed Andy Murray finally found top gear as he demolished doubles partner Marcos Baghdatis in straight sets in the quarter-finals of the Brisbane International on Friday.

Murray exploded out of the blocks to break the Cypriot's first two service games and never looked back as he wrapped up the match 6-2, 6-4 in just 65 minutes.

The world number four will now play rising Australian star Bernard Tomic in the semi-finals after the 19-year-old eighth seed disposed of Uzbekistan's Denis Istomin 6-3, 7-6 (7/4).

It was a welcome return to form for Murray, who looked sluggish in his first two matches and struggled to beat unheralded opponents Mikhail Kukushkin and Gilles Muller.

But in searing heat at the Pat Rafter Arena, the Scotsman lifted his game significantly against Baghdatis and stamped his authority on the tournament with a dominant display.

Murray broke Baghdatis twice in each set and was largely untroubled on his own serve, facing only two break points in the entire match, and saving both.

"I played very well today in hot conditions," Murray said.

"I felt like I moved very well right from the start which wasn't the case in my first two matches. That's a huge part of my game and when that goes well the rest of my game improves a lot.

"I can dictate more of my points and make it harder for my opponents to get the ball through me and that's what I did from the start."

Murray said his slow start this week was simply a case of needing time to get used to the courts in Brisbane.

"It took me a while to get used to the conditions," he said. "Playing in practice is completely different to the matches and sometimes your legs are a little bit heavy and sometimes there are nerves.

"I hadn't played for six or seven weeks and it takes time to get used to it again."

Murray said his tough doubles match alongside Baghdatis on Thursday had ironically helped him beat the Cypriot 24 hours later.

"I thought it probably sharpened me up a little bit, it was a high standard doubles match with quick reflexes and I felt I had a little bit more time on the ball than I did in the first couple of matches," he said.