Rather than welcome in a new year, controversial Croatian Marin Cilic has embraced a new beginning at the Brisbane International.

And in just his second tournament since returning from a doping ban, Cilic already feels like the misery of 2013 is behind him.

Buzzing under the guidance of his new coach – Wimbledon champion Goran Ivanisevic – Cilic moved into the Brisbane International quarterfinals by upsetting fifth seed Grigor Dimitrov 7-5 7-5 in the second round on Wednesday.

The former top 10 player – now ranked 37th – made short work of 2013 Brisbane finalist Dimitrov as he tried to make up for lost time.

World body the ITF handed Cilic a nine-month ban – later reduced to four by the Court of Arbitration for Sport – after it claimed he tested positive for a banned stimulant which the Croatian admitted ingesting via an over-the-counter glucose supplement.

“Feels still the same career but it feels like a new beginning for me,” Cilic said.

“I’m thinking about everything around myself in a different perspective.

“I had a lot time to think about everything and time to work. Probably as you saw, I improved my serve – that was something special from Goran.

“But of course I’m excited to be in the season and to play, to be back on the tour after all that misery last year.”

A long road still lies ahead for Cilic as the 2010 Australian Open semi-finalist looks to reclaim his former glory.

But Cilic believed he had the best guide – Ivanisevic.

“I would say all the things that he went through many more times than I did already in my career he can show me and tell me ‘okay, be careful of this’,” Cilic said.

“He’s going to be one step ahead of me in some situations.

“I think he knows the game and he knows what I need to improve on. I think he’s the right guy to help me.”