Brisbane: World No.5 Kei Nishikori says his experience of having to fight for everything when placed as a 14-year-old at a tennis training academy in Florida honed the determined streak which has earned him the reputation as one of the game’s fiercest competitors.

Japan’s Nishikori, who stands 178cm in an era in which tall players dominate, incredibly has the best win-loss record in deciding sets of any man in the modern era, having won 78.4 per cent of 88 deciding third or fifth sets in his career, reports news.com.au.

No man in the 45-year Open era has a better rate when tension and fatigue is its highest, with Bjorn Borg (second) having won 74.8 per cent of his deciding sets and Novak Djokovic third with 73.4 per cent.

“I don’t know where I built that from. I always to focus and never give up,” Nishikori said Friday.

Not much has come easily for Nishikori, who arrived here as the second seed for the Brisbane International behind Roger Federer.

His family prepared for his tennis career by sending him to Florida to train full-time at Nick Bollettieri’s IMG Tennis Academy at the age of 14 and his career has been interrupted by wear-and-tear injuries.

“When I was younger I was always learning how to fight at the IMG Academy and playing against many different type of players. I learned to earn things. So maybe there I learned this,” he said.

“Every tournament is important to me. The last couple of years I started the year in Brisbane. I decided to do this again and I will try to prepare as good as I can for the Aussie Open.”