Collins enjoyed a career-defining run to the 2022 final at Melbourne Park before falling to Ash Barty, less than a year after undergoing surgery for endometriosis to have a cyst removed.
She came into the opening grand slam of 2023 battling a knee complaint and was forced to call for a medical timeout midway through the first set on Monday against Anna Kalinskaya.
The Russian had bowed out in the opening round in her three previous Open campaigns, but for long periods of Monday's clash she looked likely to break her duck.
In the end, Collins prevailed 7-5 5-7 6-4 in a match lasting a tick over three hours.
"I've played a couple of these matches recently, and didn't pull out the win," said the 29-year-old.
"Any time you're on the court playing three-hour matches, you especially want to win, putting in that much effort.
"I just needed to push through the hurt a little bit.
"I definitely had a scare in the first set with the injury, which is not what you want to be dealing with in the first round of a tournament.
"I was able to work through it and the physios were really helping me."
Collins is something of an open book on the court and several times in the nerve-wracking final set she struggle to hide her frustration as Kalinskaya painted the lines with a string of winners.
"The finish, it was tough," she said.
"There's a saying, right, 'you'd rather be lucky than good'.
"Well, she was good and she was lucky.
"She was playing some really, really good tennis at a super-high level, challenging me and pushing me back.
"She didn't give me many free points, that's for sure.
"So I really had to find my game within that and bring my targets in a bit."
The 13th-seeded Collins' second-round opponent will be Czech Karolina Muchova, who trounced Ukrainian qualifer Lesia Tsurenko 6-2 6-1.
