The Spaniard has gone just 4-4 since reaching the semifinals at the French Open, including a humiliating loss to Karolina Muchova in the second round of the US Open, but put together a fine effort in her opener in the Far East.
Muguruza sharp to claim opening set
Both players confidently held to start the match, each sealing their opening holds with an ace, but it was Muguruza who made the breakthrough in the next game courtesy of four forehand errors and a double fault by Bencic.
Down 3-1, the Swiss fired what she thought was a winner on break point, only to see the ball drift fractions long to fall behind a double break. She got one of the breaks back with a backhand winner only to see the Spaniard play some outstanding defense to regain her double break advantage.
Serving for the set at 5-2, the two-time major champion needed four set points before a booming body serve forced Bencic back and wrapped up a first set that saw Muguruza's first serve percentage at 74% while taking three of four break points.
Spaniard closes strong to advance to second round
The second set saw Bencic pick up her level of play, keeping up with Muguruza through the opening four games as the two players produced some outstanding rallies, but a fine backhand passing shot by the Spaniard on break point in the next game gave her a 3-2 lead.
With some help from a couple of net cords, the Swiss held a 0-40 lead on the Muguruza serve and broke when the Spaniard flew a forehand long. After a grinding hold of serve, the world number 39 had inched ahead 4-3.
The eighth seed battled for a hold to even the set and summarily broke after overcoming a 40-15 deficit. A backhand winner set up break point and she duly took it when Bencic hit a backhand of her own into the net.
Serving for the match at 5-4, Muguruza fired a forehand winner that was just in on her second match point to close out an impressive victory. She faces either Eugenie Bouchard or Alison Riske in the second round.
Assessing the match following her win, Muguruza described the encounter as a "very difficult first round. Tough player with incredible wins. Today was tough but I’m glad to win." She added that "I like to play here. In the past I've done well (2015 finalist), so I'm positive this year that I can do well again and go far."