Nick Bollettieri: Lendl earns his corn but now it's another giant test for Murray

The Wimbledon Files: Murray's ability to be relentless with his groundstrokes will be decisive

For Andy Murray's sake it's a good job they don't have a high-speed roof at Wimbledon. It takes an age to get that thing shut but that worked in Murray's favour on Saturday night – what a difference a delay can make.

It was like two different matches and, thankfully for Murray and all you guys in the UK, he got the second one spot on, which is why he's back for this afternoon's showtime against Marin Cilic. Holy cow, do they breed them big in Croatia – Cilic may be smaller than Ivo Karlovic but this boy is still a towering 6ft 6in and this is going to be a big challenge for Murray.

First let's tie up Saturday night because this was an important moment in the Murray/Ivan Lendl relationship. Before the roof was closed, Murray was slicing the majority of his backhands and every one of them was aimed cross court. That was a huge mistake. He was becoming frustrated too and there were a couple of tumbles. They were bad ones and could easily have ended his Wimbledon there and then. It was not far from disaster.

So what did Lendl do? He earned his corn, man. He made Murray slice down the line and become much more offensive with the two-handed backhand, including down the line as well. His passing shot, one of the game's best, was back and Murray began to tick. The Murray passing shot gets so low over the net that it forces the opponent to hit up on the ball, and that makes it easier for Murray to take control of the rally.

Marcos Baghdatis – a great friend of Murray's, by the way – got his tactics wrong. He came in, but hesitantly. If you make a commitment to come to the net you give away the lob – but put your nose on the net and let them lob and you will come out way on top over the course of a match.

Cilic is a different player. He has weapons. Baghdatis hit some good forehands but he didn't have a consistent weapon. Cilic is a guy who many picked out a few years ago as part of a group of players who could one day dominate.

He's always had the potential but there comes a time when that has to become something more solid. You want to see the results in black and white. Promise doesn't win prizes. His record in the Slams isn't great – there's a semi-final in the US and this is the second time he's reached the fourth round here. But he can do it. He's got the skills; he keeps good control, is a big boy physically so is not going to be out-hit, and he moves well. As with all the top players, he doesn't really have a weakness you can pick on.

Overall that match on Saturday helped Murray – it was a good win and his serving after the delay was real impressive. But there is a potentially key question – how sore is Murray? He was like Boris Becker tumbling around on that grass out there but I'm not sure he's as robust as Becker. Murray will have to be healthy. He would have a legitimate case if he has got a leg injury, and if you doubt that then just watch the footage back. That was a dangerous fall. This will not be an easy match – this will not be one, two, three sets and then home. The ability of Murray as it goes on to be relentless with his groundstrokes will be the deciding factor. The consistency and the way Murray covers the court will give him the edge.

Both have to get over big efforts on Saturday, but they will. With the adrenalin flowing, tiredness won't mean a thing. It's like jet lag – it's a load of bull, man. If you can't get up for this, pack up the racket. Will Murray be ready? Absolutely. Will Cilic be ready? Absolutely. This is Wimbledon. Game on.

Today's big match: Andy Murray v Marin Cilic

HOW THEY MATCH UP

UK Nationality Croatia

25 Age 23

London Residence Monte Carlo

Right-handed Plays Right-handed

6ft 3in Height 6ft 6in

4 World ranking 18

22 Career titles 7

$20.6m Career prize-money $4.9m

30-6 Wimbledon record 8-5

Semis 09/10/11 Wimbledon best 4r 08/12

5 Head-to-head 1

1/4 Odds 11-4

Bollettieri's prediction: Murray in four

COACHING REPORT: Maria Sharapova v Sabine Lisicki Lisicki must hit hard to keep that winning smile

Boy, it's good to see the smile back on Sabine Lisicki's face. She spent a week at the IMG Bollettieri academy before coming over to England; when she arrived she was in all sorts of trouble. Her confidence was shot, man, and that's what this girl is all about. I took her aside at the academy and told her: "Stop feeling sorry for yourself, stop making excuses."

Part of the problem was she knew coming into Wimbledon that she had all those points on her world ranking to defend, having got to the semi-finals last year. She was nervous about going out early – but here she is, start of the second week and looking so much more relaxed.

Her form has not been great; she still mixes a good set with a bad one, as she did in the last round against young Sloane Stephens. That is in part because she only knows one way to play – hit the goddamn thing. That's what we told her to do at the academy a few weeks back: "Sabine, get out there and hit it." That's what she can do and she will have to do it if she is to have a chance this afternoon.

Maria Sharapova beat her in straight sets in the semis last year. Of course she hits it hard too, but you know where the big difference is? It's where it always is at this level: upstairs. What Lisicki has got to do is come out firing – pow, pow, pow. Try to unsettle Sharapova.

Expect short points – but also expect Sharapova to win. She has that winning mentality, and that counts.

Thoughts for the day

A pixel perfect week

I have to say a big thank you to all the guys at BBC radio. I had a ball with them this last week and on Saturday they gave me a gift – an autographed photo of the entire team.

A special night at a special venue...

I had another big gift this weekend. Last night the US Tennis Association put on a dinner for me to pick up an award for services to tennis from the International Tennis Federation. I was really honoured. It was at Queen's Club and, by the way, you guys have some real special places to play tennis.