The 34-year-old three-time major winner, who underwent career-saving hip surgery, has now strung together four wins in a row for the first time since being crowned champion at Antwerp nearly three years ago.
He again was exceptional against towering Reilly Opelka at the Sydney Classic, battling through their semi-final 6-7 (6/8), 6-4, 6-4, successfully blunting the American’s giant serve.
Murray, who has been given a wildcard into next week’s Australian Open, said he was encouraged by how he was playing heading into the opening Grand Slam of the year, a tournament where he is a five-time finalist.
“It would be amazing to start the year with a win, it’s already been a great week for me,” said the Scot, now ranked 135, who closed his eyes and let out a huge roar on winning the match.
“It’s big progress from anything I’ve done in the last year or so. To string four matches together like this, against a couple of top players,” said Murray, setting his sights on a 47th career title.
“I’ll go for 47 tomorrow. I’ve played better with each match and hopefully I step it up again tomorrow.”
He will face world number 20 Karatsev who came through a 3hrs 6mins epic against Briton Dan Evans 6-3, 6-7 (13/15), 6-3 to make Saturday’s final.
World number four Barbora Krejcikova saved seven match points to edge an epic third-set tie-break against Anett Kontaveit and storm into the women’s decider.
The French Open champion looked out for the count when she lost the first set to love against the seventh-ranked Estonian, but refocused to take the match into a deciding third.
It could have gone either way in a high-quality toe-to-toe encounter from two of last year’s most improved players, who signalled they will be a real threat at next week’s Australian Open.
But it was Krejcikova who eventually triumphed 0-6, 6-4, 7-6 (14/12) after 2 hours and 30 minutes on her fifth match point, after saving seven, to prevent Kontaveit from reaching her fourth final in a row.
She will play Spain’s world number nine Paula Badosa in the final after she cruised past 26th-ranked Russian Daria Kasatkina 6-2, 6-2.
“I just planned to fight more and try and stay in the match,” Krejcikova said on her comeback from a first-set bagel.
“I felt that at some point I would get my chances and it was important to convert them. I had to find a plan B and I’m really happy that I did. It was a wonderful match.”
Both players were newcomers to the season-ending WTA Finals last year, where they had their only previous meeting, which the Estonian won in straight sets en route to the final.
That victory was part of Kontaveit’s stellar year-end run, where she won 28 of her last 32 matches.