Ruzic, ranked 67 in the world, was initially beaten in the qualifying first round by Rebecca Sramkova last week but earned a spot in the main draw with seven prominent players, including Aryna Sabalenka and Iga Swiatek, pulling out.
The 23-year-old was rewarded with a clash against 2021 U.S. Open champion Raducanu after Elisabetta Cocciaretto's injury, and she made the most of her time under the spotlight, sealing a 6-1, 5-7, 6-2 victory on Monday for her first career top 30 win.
"The whole turnaround was crazy," Ruzic said.
"I was a lucky loser who had lost in the first round of the qualifiers. A lot of the girls were cancelling and a lot of them were not here to sign (as alternates). I was like 'OK, I'm going to sign and let's see what happens'."
Ruzic explained she and her compatriot Petra Marcinko - who also received an entry into the main draw as one of seven lucky losers - had remained in Dubai as they were playing the doubles tournament together.
"We were going to stay here for two-three days. It's crazy because I got in on Monday. Playing against Emma, of course, is a tough match," Ruzic added.
"We played three sets of good tennis and it was a battle in the third. I'm happy I managed to get it under control and that I won in the end."
Defeat ended world number 25 Raducanu's disappointing spell in the Middle East hard court swing, with the 23-year-old seeking medical attention midway through the match against Ruzic for an unspecified issue.
The former world number 10 struggled with illness in her Qatar Open first-round match with Camila Osorio last week, when she was forced to retire in the third set while trailing by two games to love.
Briton Raducanu reached the final of the Transylvania Open earlier this month and was beaten by Sorana Cirstea.
