It is exactly three weeks since Murray lost out to Roger Federer in the Wimbledon final on Centre Court, and the world number one was in Wawrinka's box to support his countryman, who is both a friend and a familiar foe of Murray.
The pair, who practised together last week, had met 10 times before, with the British number one winning six times, including a five-set epic under the roof at Wimbledon three years ago.
That was the first match to be played entirely under cover, and the roof was on again for this contest.
Murray secured the first break of the match in the eighth game with a backhand down the line.
Both players had begun a little tentatively, but Murray improved significantly as the set went on and served it out to love with an ace.
Things got even better for the third seed with another break at the start of the second, his fourth game in a row, and he saved a break point to make that five.
Murray cracked a couple of superb backhand returns as he sought a second break in the seventh game and, although Wawrinka staved off that threat, the end was not long in coming.
The Swiss found himself under pressure again in his next service game and Murray took his second match point when Wawrinka drilled a backhand wide.