Nick Bollettieri: I plead the Fifth over trying to call which of my students will win

The Wimbledon files

(REUTERS)

If you are lucky enough to be on Centre Court this afternoon – watch out. This is going to be a match of missiles. Neither Maria Sharapova or Sabine Lisicki are the type to dig foxholes, climb in and look to defend. No, sir, they will be out in the open fighting with all their might and boy, oh boy, do these two have some mighty shots.

It could not be a better semi-final for me – two players who first came to my academy when they were just girls. It's incredibly exciting for the academy to have two former students facing each other at Wimbledon with a place in the final at stake. I couldn't ask for more and it has the makings of an engrossing match between the surprise package of the tournament and the former champion who is back to her best.

Let's break their games down. Both Sharapova and Lisicki have big forehands, huge flat strokes that can push their opponent back beyond the baseline. They are both aggressive and like to hit the ball early. I would put their forehands on a par, although Lisicki may well produce more outright winners with the shot.

Their backhands are also similar. Both hit two-handed and again like to take the ball early and hit it flat. I would score this one even as well. It's also hard to separate them when it comes to volleying, although this time it's because neither of them are that keen to get into the net. They both are controlled volleyers – it's not a shot either likes to gamble on, both prefer to hit swinging volleys. It's the same when it comes to the slice – not a shot either likes to use.

Now when it comes to the serve, there's a slight edge to Lisicki. The German hits it at a greater velocity and will deliver more outright winners. Sharapova's serve is still pretty big but she looks more for placement. Lisicki's second serve is more aggressive than Sharapova's.

Lisicki likes to use the drop shot and it's one she is becoming more and more confident about, and using better and better as well. Boom, boom with the forehand and then bing, the drop shot with her opponent flat-footed deep beyond the baseline.

Lisicki also moves better, she's naturally more athletic than Sharapova and has a stronger foundation. Sharapova's movement is improving and as the courts become more worn behind the baseline that actually suits her with less grass around.

Their aggression comes out again when we look at the return of serve; they both like to hit the ball damn hard. So there we have another tie.

When you run through the skill sets of these two, Lisicki appears to have a slender advantage but then we come to possibly the two most important factors of this afternoon's game. Experience – stepping out on a packed Centre Court, one of the great arenas in world tennis, heck world sport, that is a tough call, man, I'm telling you. If you've been there before – and won – that is a big help and Sharapova has been there. Lisicki hasn't, a 2009 quarter-final here is her best at any Grand Slam. This will be the 11th time that Sharapova has lined up in a Grand Slam semi-final. A few months ago Lisicki was ranked outside the world's top 250 and she is only here thanks to a wild card – and some damn fine performances since. In the mental department you have to go with Sharapova, although I was impressed with Sabine in the way she kept her cool after missing those match points against Marion Bartoli in the second set on Tuesday. But Sharapova has handled all the crap for many years now and not much gets under her skin. She's cool, always cool.

Who is going to win? Hell, you don't expect me to pick one above the other do you? I remember once when Andre Agassi played Jim Courier – I had a foot in both camps but chose to sit in Andre's box. That was a mistake and I won't be taking sides today – but I will certainly be enjoying it.

Today's big match

Maria Sharapova v Sabine Lisicki:

How they match up

Russian Nationality German

24 Age 21

Bradenton, Fl Residence Bradenton, Fl

Right-handed Plays Right-handed

6ft 2in Height 5ft 10in

6 World ranking 62

23 Career titles 2

$15.2m Career prize-money $1.1m

W35 L7 Wimbledon record W9 L2

Winner Wimbledon best Semi-final

W1 L0 Head-to-head W0 L1

2-5 Odds 2-1

Bollettieri's prediction...I plead the Fifth, guys

Coaching Report: That was the first time I’ve seen fear on Federer’s face

Roger Federer v Jo-Wilfried Tsonga

Wow! you know what? This amazing match, Roger Federer, the great Roger Federer, two sets up and one foot in the semi-finals of Wimbledon for the eighth time, before being blown away, can be summed up pretty easily.

Number one – Jo-Wilfried Tsonga's strategy of coming forward and forcing Federer to try and pass him worked to a treat once the big French guy had nothing to lose.

Number two – and here's the extraordinary thing, I looked at the facial expression of Roger Federer, the man with the 178 and 0 record when it comes to holding on to a two-set lead on the big stage. And you know what I saw? Man, he looked scared. I have not seen that before. Never. Those two things – plain and simple – saw the impossible become possible.

Tsonga has a huge serve and even though his first-serve percentage was slightly less than Federer's – 70 to 75 – it was mighty, mighty effective. And that was throughout the match. Federer only had one break point in the entire contest. One break point! Holy cow.

Tsonga served big. His fastest reached 135mph and he averaged 121 over the five sets. That is a hard weapon to combat when it clicks as it did yesterday afternoon on Centre Court. He pushed Roger further and further back beyond the baseline and from way back there it became increasingly difficult for the Swiss master to unleash that beautiful one-handed backhand. Power was grinding down the genius. As that happened the pressure was ratcheted up on Federer and it doesn't matter who you are, pressure isn't comfortable. Tsonga was throwing fire.

I have never seen that reaction from Roger before. He looked frightened as Tsonga's comeback gathered momentum. When the second set finished after a little over an hour's play, I thought "job done" – who in the world didn't? Then Tsonga went on the attack and the boy had nothing to lose. On the other side of the net Mr Wimbledon had everything to lose and it showed. Forward came Tsonga and back went Roger. Federer got tighter and tighter and Tsonga got more and more bullish.

His win blows the draw open – Federer had looked so smooth as he progressed through the early stages. What a tournament – it's been mesmerising.

Mr B's A-Zee

S is for Serena. She may have gone home this year but her presence will always be felt at Wimbledon. She's won four singles, four doubles and a mixed doubles here. Not bad eh?

T is for what every player who starts out in round one wants, the trophy. The two big ones are the Gentlemen's Singles Trophy, which has been handed out since 1887 and is a looker of a trophy. And for the women, the unmistakeable Rosewater Dish. It's all part of the tradition.

Win a week at my academy

Want a week's tennis holiday at my IMG Nick Bollettieri Academy in Florida? Included in the prize is five days' top-class tuition. The prize can be for an adult wanting to shape up his or her game, or for a child who wants to follow in the footsteps of the likes of Andre Agassi, Monica Seles and Maria Sharapova, among other players who went from being kids under my tuition to No 1 in the world.

What you have to do is answer this question: Tell me, what will the score be in the Sabine Lisicki against Maria Sharapova match? Email your answer (and predict how long the match will last, in case we need a tie-break) to me at bolly@independent.co.uk and the correct one will win a signed hat or T-shirt.

I'll be putting a question every day and all the winners will go into the hat for the big prize to be drawn at the end of the fortnight: a week at the IMG Nick Bollettieri Academy. Tuesday's winner was Kevin McCormack.

Coaching tip of the day

From the moment you step foot on court keep an eye on your opponent. You can learn plenty about them even from the warm-up – what shots do they practise? Many players tend to warm up to their strengths, so if you don't see them volleying that can mean they are not volleyers and that's an area you can take advantage of.