You are not permitted to download, save or email this image. Visit image gallery to purchase the image.
He combined with British partner Luke Bambridge to claim a 6-3 7-6 opening win over Ajeet Rai and Mackenzie McDonald in their men's doubles opener.
McLachlan, who is from Queenstown but represents Japan, last year won alongside Jan-Lennard Struff.
He has been playing with Bambridge since the latter part of last year.
The duo now play third seeds Henri Kontinen and Rohan Bopanna in their quarterfinal today.
Meanwhile two other Kiwis advanced past the first round.
Artem Sitak and Marcus Daniell progressed, although that came at the expense of another home hope.
For the fourth time in the last five years Sitak saw Michael Venus across the net in Auckland, as the two clashed in the first round of the doubles.
"I would rather play someone else, because then the whole crowd is behind us," said Sitak.
"This time it was a little bit quiet, and it was half and half. [In the] night session and playing someone who is not from New Zealand, you feel like they are lifting you and the energy is amazing."
In contrast on Wednesday the crowd was a bit confused, not quite sure who to support.
"It felt that way," agreed Sitak. "They were loud because we had some great points but that's about it. Which is understandable because you don't really know who to cheer for, I guess you are cheering for good tennis."
Sitak and partner Divij Sharan were down a break in both sets, but fought back to win 7-6 (4) 7-6 (3) over Venus and Australian John Peers.
"It's not easy to play Mike," said Venus. "He's a top 10 player and it's very difficult to beat him all the time. This time we got through, and it's unfortunate we had to play each other first round but that happens."
Sitak and Venus have been Davis Cup teammates on numerous occasions, adding another layer of intrigue to the contest.
"It always is difficult but at the end of the day you get on court, you want to win and you just focus on what you have to do on every point and it doesn't matter who is on the other side of the court," said Sitak. "It's not ideal to play against each other but he wants to win, I want to win."
In the second set Sitak and Sharan twice trailed by a break twice, but both times retrieved it and were too good in the tiebreak, a Sitak forehand converting their second match point.
Fellow Kiwis Marcus Daniell and Austrian Philipp Oswald also progressed, though in a more unusual manner.
They were leading the Italian duo of Fabio Fognini and Simon Bolelli 6-3 1-1 when Fognini retired hurt.
The Italian had treatment for a back complaint during his upset singles loss to Feliciano Lopez earlier on Wednesday, but had also looked disinterested at times in the doubles, barely running at times and not serving anywhere near full power.
When asked the reason for the withdrawal, the Italian world No 12 said: "You know, next question."
Daniell was content, despite the abbreviated contest.
"It's always a little strange when you don't finish it off. But we actually played well. I think if we hadn't played well, then he probably would have carried on."
"We played well enough to make him not want to hang around and that's all we can do. While I feel sorry for him and hope he gets better for Australia, we can only take care of our side of the court and I thought we did that pretty well."
Even though they had seen Fognini receiving treatment in the singles, Daniell said they tried to put they out of their heads.
"That's a really dangerous thought process. We can't know what is going on in the minds of the opponent. So all we can do is get as ready for the match and treat it like they are going to go at us 100%.
"Fabio always sort of wanders around the court and has a bit of a strut so I think he really tries to get in people's heads with his slow walking and that kind of stuff. We saw it early on and kept our focus, kept our passion and it worked well."
- Otago Daily Times and New Zealand Herald