Nick Bollettieri's Wimbledon Files: Seconds out for round two of Andy Murray v David Ferrer

A word of advice from a guy who has been around the block a few times: if you're going to watch Andy Murray against David Ferrer this afternoon, pack some extra sandwiches and make damn sure you go to the rest room before the match. This is going to go some.

This is a match where the two guys could be playing in front of a mirror, they have so much in common across their games. They are both fantastic movers and great returners – Ferrer describes his return as his best weapon and Murray was booming them back at Marin Cilic yesterday.

Both guys made pretty impressive work of dealing with tough-looking opponents. Murray never appeared in any danger as he dealt with another big Croat – boy, do they breed them big out there – in quick time. Bang, bang, bang: straight sets. Same for Ferrer against Juan Martin del Potro and it sets up what could be one of the closest matches of this Wimbledon.

Ferrer showed on Centre that he is going to be very difficult to beat. Man, he's like a kangaroo out there. He likes to take a hop into his shots and he springs into action. He has such fizzing energy. But, more importantly, he played real smart against Del Potro. He moved the big Argentine around the court and kept his shots low. Del Potro had his chances in the first set but couldn't take them and, as with any top-level sport, if you don't take your chances you will get punished.

Today both men, your boy Andy and the Spaniard, cannot, I mean cannot do that. This is going to be intense, especially if that roof is shut. They are both superb athletes who have the ability to change the pace of a match. Ferrer did that well against Del Potro – look at the way he threw in the odd loopy forehand to push his opponent deeper behind the baseline.

The difference for Ferrer today will be that Murray will not falter as a rally develops, unlike some of the big guys. Murray has the mental discipline not to rush, to let the point develop – if he has to wait for the opportunity to pounce he will wait.

This is going to be about small margins. Murray knows it. Ferrer knows it. I have so much respect for both guys. This is a hard, hard match to call and it will be decided on maybe a few lucky breaks, the ability to capitalise on every break point.

Murray's progress to this stage has been impressive – good wins over a variety of tough opponents. There have been the two boom-boom matches with the Croat giants, Cilic and Ivo Karlovic, and the different challenges offered by Nikolay Davydenko and Marcos Baghdatis. All jobs well done. This is another step up the ladder, though, as you would expect in the last eight of a Slam.

Ferrer's energy will make it a big test of Murray's endurance and the work Ivan Lendl has done on the mental side. Ferrer beat Murray in the French Open a few weeks ago but that's over, baby, gone. It's absolute bull to say that will have any bearing whatsoever on this afternoon.

That was Paris, this is Wimbledon. It's a whole different world but, man, is it a tough one to call.

Today's big match: Andy Murray v David Ferrer

How they match up

GB Nationality Spain

25 Age 30

London Residence Valencia

Right Plays Right

6ft 3in Height 5ft 9in

4 World ranking 5

22 Career titles 15

$20.6 Career prize-money $14.4

28-6 Wimbledon record 20-9

Semis x 3 Wimbledon best Quarters '12

5 Head-to-head 5

4-9 Odds 7-4

Bollettieri's prediction: Murray in five sets

Thoughts for the day

Ferrer's running style helps him to gain precious time

Watching some of the action yesterday reminded me of one of my little tips to help improve your game. Watch when someone like David Ferrer goes after a wide ball. He doesn't keep two hands on the racket, one comes off so he can move more like a sprinter, push those hips and shoulders and swing that free arm.

Federer is a man who's in no mood to go home

I don't know how bad Roger Federer's back is, but this is a man who looks like he wants to hang around to the weekend. It's like Boris Becker. When he felt in form, he would arrive at Wimbledon and say: "Nick, book us in for two weeks. I'm staying till the end."

Coaching Report: Serena Williams v Petra Kvitova

It's game over when Serena's huge serve sings

Remember that Frank Sinatra number "What a difference a day makes"? Well, for Serena Williams it was "What a difference a serve makes".

Against Yaroslava Shvedova on Monday it was not all there. Yesterday against Petra Kvitova – the defending champion, do not forget – it was all there, and Kvitova had no answer. No wonder the Czech woman said afterwards that it had been tough out there – when she's on song, Serena takes some stopping.

And the key to Serena is the serve. It is the best in the women's game by a margin. I mean, holy cow, she boomed down her fastest yesterday at 120mph and averaged her first serve out at 109mph. Take this as a comparison: in his victory over Xavier Malisse on Monday Roger Federer hit his fastest at 122mph and chalked up a first-serve average of 110mph. There were 13 aces across the two sets and not one double fault.

Kvitova, no slouch herself when it comes to giving the ball a whack, was outgunned. That first set ran away from her, as Serena controlled it from the first point. "That's my game," said Serena afterwards.

She admitted she was not on her game in previous rounds but these Williams sisters, when they get on a roll they are tough, tough, tough to stop.

She returned better too, but you see, guys, that all comes from getting the serve right – when that clicks, her game clicks, full stop. Her body language was interesting too. When Serena plays, watch those shoulders. In the previous rounds there were moments when they slumped. Yesterday? They stayed up and she stayed up. What a difference, Serena.