Even for his standards, the shot Roger Federer produced in his second round Australian Open match was unbelievable.The shot, which came during his match with Filip Krajinovic, saw a cross-court shot with the Swiss star at maximum stretch.Krajinovic could only stand and stare as he watched the ball narrowly stay within the limits of the court.Having advanced through Steve Johnson and now Krajinovic, Federer's path through the tournament has cleared up slightly following the latest set of matches.Fabio Fognini and Guido Pella are the only seeds the Swiss star can face in the quarter-finals and his route to the last eight is clear of top-32 stars.Hoping to pick up his 21st Grand Slam title in Melbourne, the 38-year-old will likely have to beat Novak Djokovic and Rafael Nadal back-to-back.Despite this, a number of upsets have eased his latter rounds.Former world number three Grigor Dimitrov, a potential fourth-round opponent, was edged out of a championship tie-break after a five-set thriller against Tommy Paul.Having not lost a first-round match at a Grand Slam in 20 years, Federer explained the reason behind his early tournament performances.

Federer said: "I guess there is a few reasons that - you know, some were close, let's be honest. There are a few that pop up in my mind right away.

"I think also I became a better player. 32 seeds helped, you know, to keep more of those better-ranked players away, as when I came up on tour there was only 16 seeds and all that.

"Yeah, then I guess I created a game which allowed me to manage maybe all kinds of opponents, you know, that were ranked outside of the top 30 in a first round like that even if there is rust or there is nerves and so forth.

"Look, I'm happy that I was able to manage those first rounds. As we know, they can always be very tricky.

"That's why Masters 1000 are tough sometimes. You can play a top-20 player in the first round and that's when it gets tough."