But Nishikori, who had lost nine consecutive ATP finals over 52 tournaments in almost three years, broke the Russian player's serve on four consecutive points in the final game to clinch the match in just 2 hours, 6 minutes, at Pat Rafter Arena.
After his impressive straight sets quarter-final win over Grigor Dimitrov, Nishikori said he had set his sights on returning to the world's top five after falling to 39 last April due to a wrist injury at the end of 2017 that forced a break from the tour.
"If I'm being really frank, I just feel like I had the worst attitude today". Playing with these guys, these top players, always motivates me.
Any thought Medvedev would take the momentum into the decider proved wrong as Nishikori stormed to a 5-1 lead, eventually wrapping up the final in just over two hours.More news: Is this the iPhone XI for 2019?
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Former world number one Karolina Pliskova lost her way midway through a "strange" encounter with Ajla Tomljanovic on Friday, before recovering to blaze past the Australian 6-1 1-6 6-1 and into the Brisbane International semi-finals.
Momentum seemed to have swung away from Nishikori, who survived a scare to hold serve at the start of the third, but the Japanese reeled off four games in a row to move 5-1 ahead.
"Maybe first match [against Denis Kudla] was a little bit tight, but after Dimi's [Grigor Dimitrov] match and today's match was nearly flawless, I would say".
Nishikori got a near three-year-old monkey off his back with the defeat of Russia's Daniil Medvedev at Pat Rafter Arena, the title snapping a run of nine finals losses since his last tour win in February 2016.
The unseeded Tsurenko looked headed for the biggest win of her career when serving for the match at 5-4 in the second set, only for Pliskova to come storming back to win 4-6,7-5, 6-2 and claim her second Brisbane title. "So I think like that was sort of my main problem today. Hopefully this isn't like a recurring thing".