Federer fans in the crowd notice that the camera is focusing on them so they give us all a wave, unashamed by their red wigs and face paint. 

They've another reason to smile as Federer's improvised volley wrong-foots Berdych and allows him to skip merrily to 15-30 via a follow-up backhand volley. The Czech did little wrong in that point. 

From 15-30 to 40-30 to deuce, a double fault again Berdych's undoing, but the Czech wriggles free, which is good news for those who want more than three sets. 

Federer keeping apace with Berdych in terms of aces produced, the Swiss delivering his eighth of the match on the opening point to equal Berdych's tally. 

This game a free lunch for the former champion, volleying his way to parity. A hold to love completed in under 70 seconds. 

Image source, EPA

Federer isn't down for long... the backhand doing the damage as Berdych nets on his forehand side. 30-40. Break point Federer. 

And the Czech surrenders with a whimpers, a double fault and his previous good work is undone. 

Federer's serve gets him back to 30-30, and he must dig deep again to wipe out a Berdych break point, which he does thanks to his,  you guessed it, serve. 

The Swiss, who was playing dreamy tennis in the opening two sets, going through a blip, presenting Berdych with another break point - and this time the Czech's backhand finds the line. Well, I never. 

So, at 34 years 176 days, Federer is on course to become the oldest man to reach the semi-finals at the Australian Open since Colin Dibley (aged 35 years 105 days) in 1979. Unless, unless, Berdych can produce an astonishing comeback. The Czech holds to love, a positive attitude in adversity.  

Image source, Reuters

Federer playing other wordly tennis, holding to 15 to go two sets up. Berydch can do little to halt the Swiss in this form. 

Federer pulling the strings, dragging Berdych to the tape and then, with his prey stranded, passing him with a sumptuous half-volley down the line. Rightly, some sections of the crowd whistle in admiration.

The Swiss on a march, the Swiss 0-30 up. Oh. Scrap that bit about marching, Berdych has battled back to 30-30. 

Hang on, Federer has a break point and the former champ classily secures the break - wrong-footing Berdych with a backhand full of spin and dice, then sending the Czech to the other side of the court where he can do nothing but net. 

Federer upping the ante, producing his fastest serve of the match (204kmh), to open the game. 

Oohs from the spectators as Federer knocks over a half-volley from his shoe laces and claims the point with a simple volley. 

It looks as if the second set will be Federer's. Berdych not getting a sniff on the Swiss' serve. 

A rare error on the Federer backhand as he attempts to ping another winner down the line. Berdych commandeering this game, 40-15 to the good. On what happens to be the final point, the Czech defends superbly and though Federer has oodles of time to place a crosscourt forehand beyond Berdych, the Swiss nets. That's the end of that. 

Federer must beware the Berdych forehand, though he probably already knows that. There's no need for me to tell him, the man has won 17 Grand Slams. 

The Swiss reins in the Czech from 0-30 to 30-30, ending a 17-shot rally with a brilliant crosscourt forehand winner to level. 

An ace follows - Federer's seventh of the match - and the third seed brings a tricky game to an end with a feather-soft touch at the net. 

A shuffle along the baseline, fabulous footwork, and Federer unleashes a dreamy forehand winner to restore parity at 30-30. 

Federer has the Swiss floundering with a peachy backhand return, the former champion looks to have botched his chance with the court at his mercy - but the Swiss challenges and, cor blimey, his forehand kissed the line. Berdych can do little else but laugh. When you're in a purple patch, you're in a purple patch. 

Undeterred, Berdych blocks out the last couple of points to wriggle free from deuce. 

Federer gliding around the court, dictating play now, swinging freely and hitting with freedom. An easy-peasy hold and the pendulum firmly in Federer's corner. 

Federer in control at 30-0, but Berdych comes up with the quickest serve of  the match so far - a 135mph ace to reduce the arrears. Another ace follows. Bang, bang, debt wiped out in the blink of an eye. 

Deary me. Berdych messes up a makeable backhand volley, gifting Federer with a break point, and the Swiss takes it - a gorgeous backhand winner down the line. 

Image source, Getty Images

Where are we? What's happening? Ah, yes, Melbourne Park, men's quarter-final... another "come on" from Federer as a dreamy volley forces Berdych wide and brings up two set points. 

A few watery eyes in the crowd, some wince as they the ball hits an umpire in a sensitive area. Ahem. 

A beautifully hooked forehand from Berdych, but all that shot does is delay the inevitable as on the next point a Berdych forehand clips the net and drops into the tramlines.  

A stentorian "come on" from Federer this time as he threads a backhand down the line for a 4-1 lead. 

But Berdych reduces Federer's lead as the Swiss' backhand bounces beyond the baseline. Federer challenges, but replays show the ball was out by a distance. 4-2. 

Image source, Getty Images

Take that, says Federer, as he scampers right and comes up with a brilliant crosscourt forehand winner. 

A lengthy rally on the next point... Federer advances, Berdych under pressure, goes long, long, long... "Come on," yells the Swiss. 2-0 

A mini break to Federer, though Berdych halves the deficit with another ace full of menace. 2-1

Federer starts an angry monologue at the back of the court as he balloons a backhand on the opening point. Berdych in no mood to give the Swiss a chance as a howitzer of an ace eases him to 40-0. 

The Swiss nicks one point from the Czech, but a long return means we're into a tie-break. 

A feather-soft drop shot drags Berdych to the tape and the Czech should have passed Federer but, instead, he volleys straight at the Swiss, who simply pats the ball to complete a hold to 30. Is that the waft of a tie-break that I can smell?