When Grigor Dimitrov signed up to be part of Roger Federer’s new sports management agency just over two years ago, he might have assumed the time would come when he could take over from the old man.

But as Federer enters his 35th year, the Swiss is still competing for grand slam titles while Dimitrov has yet to fulfil the potential he first showed the world when he won the junior Wimbledon title in 2008.

The pair meet in the third round of the Australian Open here tomorrow and Federer, who beat Alexander Dolgopolov 6-3, 7-5, 6-1 yesterday, leads their head-to-heads 4-0, including a tough three-setter in Brisbane just a couple of weeks ago when Federer was struggling with flu.

Dimitrov reached the final in Sydney last weekend and Federer expects a tough examination.

“Honestly, Brisbane overall was tough to judge in the sense that I was just playing within myself, trying to sort of get through the matches without too many long rallies,” Federer said.

“So it's hard to think back at the matches and think like what went well and what didn't go so well. I think maybe it’s the coaches that can remind me of these things, and I might go back in time when I was feeling actually normal against Grigor.

“I think he did well in Sydney, and that definitely also gave him a bit of a lift if he takes the positives out of the tournament, because wasting match point in a final is not a great thing.

“I have gone through spells of these and they are the worst. If you look at the positive side, he should have, could have won the tournament. So he's on a high right now, as well. I think it's a tough draw, to be honest. He's got the game to be really dangerous.

“He's fit enough for a five-setter, so, yeah, I’ve got to definitely bring my best game to the court on Friday.”

After a tough year off the court, with a high-profile break-up from the most high profile of girlfriends in Maria Sharapova, Dimitrov looks settled again and in form.

His 6-3, 4-6, 6-2, 7-5 win over Argentina’s Marco Trungelliti was not as fluent as he would like but the Bulgarian is carrying some confidence.

“Obviously it's not an easy match,” he said. “But I feel that I've been playing good. I have quite a few matches behind my back already.

“It's an exciting match for me, to be able to get to the third round and play against him. You know, it's a good start.

“I'm out here to perform the best way I can, and hopefully I can play better tennis than in Brisbane, maybe do couple of things different that I thought I could have done back then.”

His three-set defeat by Federer in Brisbane came when the world No 3 was battling flu but Dimitrov said he would not be overawed.

“I think even if there's something with him, he always plays well,” he said. “I mean, he never shows the opponents that he's down or anything like that. I also felt that I had my chance, I think, even after winning that second set.

“But we all know how he plays. Tremendous competitor, all that. So, I mean, it's a match that I want to play. I definitely want to get out there on the court and sort of have a rematch - with a different outcome, I hope.”

Twelve months ago, Andreas Seppi put Federer out in the third round; this year, he has world No.1 Novak Djokovic but in the Serb’s current form, another upset seems unlikely.

Djokovic, chasing a sixth Australian Open title, cruised past French wildcard Quentin Halys 6-1, 6-2, 7-6, looking supremely confident once more.

The Serb has been super cool here so far but last night he got a bit tetchy when he was questioned about a story in an Italian sports paper, TuttoSport, which claimed he may have deliberately lost a match in Paris in 2007.

At the time, Djokovic said his straight-sets defeat by Fabrice Santoro had been influenced by recent surgery to remove his wisdom teeth and last night, he was irritated by further enquiries.

“Especially these days when there is a lot of speculation, this is now the main story in tennis, in the sports world,” he said.

“There's going to be a lot of allegations. I have nothing more to say. Until somebody comes out with the real proof and evidence, it's only a speculation for me.

“Anybody can create a story about any match. That's my point. There haven't been too many matches where top players lost in the last decade or so in early rounds.

“You can pick any match that you like that the top player lost and just create a story out of it. I think it's not supported by any kind of proof, any evidence, any facts. It's just speculation. So I don't think there is a story about it.”

Home favourite Nick Kyrgios also impressed in a 6-4, 7-5, 7-6 win over Pablo Cuevas of Argentina and now plays sixth seed Tomas Berdych.

There was disappointment for Scotland’s Colin Fleming in the doubles as he and Israeli partner Jonathan Erlich lost 6-4, 3-6, 6-3 to Fernando Verdasco and Robin Haase in round one.

Jamie Murray and Bruno Soares, the seventh seeds, were due to play England’s Jonny Marray and Aisam-Ul-Haq Quereshi overnight.