Dimitrov is pushing the limits for a strong 2017 season

At first glance, the 2016 season for Grigor Dimitrov wasn't bad. After all, a positive record of 39-26, rising more than 10 ranking spots and reaching the final of three tournaments—Sydney, Istanbul and Beijing—could never be called a bad season. However, to the 25-year-old Dimitrov it wasn't nearly enough.

It was the second season in a row without a title win for the Bulgarian, who also hasn't been inside the Top 10 since August 2014. His Grand Slam performance was also lacking compared to just two years ago, only reaching the round of 16 at the U.S. Open.

Dimitrov doesn't just want OK, he wants outstanding. That's why his off-season regiment, as documented by the ATP in a two-part series, is so intense.

"One of the scariest things for any athlete I think is pretty much the off season," Dimitrov said.

The world No. 17 described the off-season as "putting fuel in the tank."

"When you get off to the next year, you have to play a lot of tough matches," he said. "During the year, there is going to be a lot of heat so you need to be prepared."

Hopefully, his hard work will pay off with perhaps a Masters title or another Grand Slam semifinal appearance.

In Brisbane, Dimitrov started the season off right with a straight-set victory against Steve Johnson. On Thursday, he beat Nicolas Mahut to advance to the quarterfinals.

Follow Niko on Twitter: @nikovercelletto