Andy Murray came through another tough test at the Brisbane International as he fought back from losing the first set to beat Gilles Muller.
The world number four won their second-round match 4-6 7-6 (7-4) 6-0 to clinch a quarter-final with Marcos Baghdatis.
Murray struggled in his first-round win over Mikhail Kukushkin and world number 54 Muller also proved challenging.
New coach Ivan Lendl will join him this week as Murray gears up for the Australian Open.
The Scot, 24, lost the first set after being broken in the final game by Muller.
The pair traded breaks at the start of the second set and, after enduring some nervous moments to hold his serve, Murray won the tie-break in convincing fashion.
Murray then broke Muller three times as he cruised through the third set and into round three.
But with the contest lasting two hours it was another testing workout for Murray, who was playing only his second match of 2012.
"I felt I moved better in the second and third sets and that's such a big part of my game," said Murray.
"I was happy to get the win - the more matches I can get this week, the better. I thought once I got into the baseline rallies I felt good but he served very well, especially for the first couple of sets and I just managed to hang in."
The Brisbane International is Murray's first tournament since he withdrew from the ATP World Tour Finals in London in November with a groin strain.
He was also troubled by back and knee problems on the way to his round one win over Kazakhstan's Kukushkin.