MELBOURNE, Australia -- On the eve of the Australian Open, Novack Djokovic was asked if he had noticed anything different about Andy Murray.
"He has a shorter haircut," said the five-time Grand Slam winner, smiling.
But the top-ranked Djokovic turned serious because Murray's makeover is no joking matter.
The 25-year-old player from Scotland is attempting to win a second consecutive Grand Slam after a breakthrough year that included wins at the London Olympics and the U.S. Open. He arrived in Melbourne with a new demeanor, a sense of calm and confidence.
"I think mentally something switched in his head," said the top-seeded Djokovic. "And he just started believing much more in his abilities.
"Now that he's done it, he's definitely right up there, one of the first few favorites for any tournament he plays."
On Wednesday, the third-seeded Murray advanced to the semifinals to take his spot in an all-star lineup featuring the top four players.
Top-ranked Djokovic has the first semifinal against No. 4 David Ferrer, who took the spot in the absence of an injured Rafael Nadal.
Third-seeded Murray faces No. 2 Roger Federer for the latest rematch in a tight rivalry. Murray leads Federer 10-9 in career matches, including at last year's Olympic final. But he has played the Swiss star in three Grand Slam finals and lost them all.
"I'm expecting a tough match," said Federer, describing Murray as clever and tactical. "He's changed his game around a bit. He's playing more defensive. I'm looking forward to it."
Federer is aiming for his 18th Grand Slam. The Swiss star stamped his authority on center court by beating the athletic Jo-Wilfried Tsonga 7-6 (4), 4-6, 7-6 (4), 3-6, 6-3 to reach the Australian Open semifinals for a 10th consecutive year.
After losing, Tsonga picked his favorite to win: "I would say Andy, for the moment. But it could change, of course."
Murray won his quarterfinal against Jeremy Chardy of France 6-4, 6-1, 6-2 to extend a streak of straight-set wins into the semis. Of all the men in the draw, Murray is technically the freshest, having spent less time on court -- just under 9 hours in the past 10 days.
Chardy walked into his post-match news conference saying he couldn't believe how well Murray had played.
"I've played him several times, and every time I always thought I had a chance," said the 36th-ranked Frenchman who beat Murray in August in Cincinnati. "Today, he never let me think even once I had a chance to win.