None of the three leading players has lost a set in the tournament.
Federer punctuated his 54-minute victory with a Pete Sampras-like jumping smash after Soderling tried to flick a lob over him. Soderling's 14th loss in 15 matches against Federer was his worst. It also was his most one-sided defeat since April 2009 when the Swede took only one game off Nadal at the Rome Masters.
No. 2-ranked Djokovic beat Guillermo Garcia-Lopez 6-2, 6-3. The Serb broke early in both sets and fought off two of the three break points he faced.
Garcia-Lopez downed Nadal two weeks ago on his way to capturing the Thailand Open. He had won 10 of his last 11 matches, including a victory over seventh-ranked Tomas Berdych in the third round.
No. 4 Murray handled an error-prone Jo-Wilfried Tsonga 6-2, 6-2. The Scot dominated with big serves and delicate drop shots. He broke the 12th-seeded Frenchman four times and lost only eight points on his serve.
"I served well and didn't give him any chances on my serve," Murray said. "I was hitting the ball really cleanly from the back of the court, so it was a good start."
Tsonga recently returned to the tour after a three-month injury layoff. He struggled to keep the ball in play, making 21 unforced errors and five double-faults. He's lost seven of his last eight matches against top 10 players.
Murray rebounded last week from an illness that had dogged him since the U.S. Open. He will next face Monaco, defeated Melzer a week after losing to him in Tokyo.
Monaco reached his first semifinals since February. After the French Open, he was off for three months because of an injured left wrist and ended a five-match losing streak on tour this week.