Great Britain's Andy Murray and Joe Salisbury beat Nicolas Mahut and Pierre-Hugues Herbert to reach the second round of the men's doubles.
The British duo produced an impressive performance to knock out the second seeds 6-3 6-2 in one hour 15 minutes at Tokyo's Ariake Tennis Park.
However, Heather Watson exited in the first round of the women's singles, beaten by German Anna-Lena Friedsam.
Friedsam won 7-6 (7-5) 6-3 in one hour 49 minutes.
"It definitely wasn't my best tennis but I gave it my best with what I had," said Watson. "It just wasn't enough.
"There were too many unforced errors that came and went in waves. I am just very disappointed with the outcome.
"I did everything I could to prepare right and I literally could not have done any more. I felt really good going out there."
Murray and Salisbury face German pair Kevin Krawietz and Tim Puetz in the next round.
"I think we have the potential to be a really good team," said Murray, who begins his singles campaign against Canadian ninth seed Felix Auger-Aliassime on Sunday.
"We were well deserved winners today - we created lots of chances - but not every doubles match is like that.
"If we keep the same sort of attitude and everything, prepare diligently, I think we've got a chance of doing well."
Jamie Murray and Neal Skupski also play on Saturday when take on Argentina's Andres Molteni and Horacio Zeballos in the men's doubles.
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