Andy Murray column: 'Players get nervous watching matches'

When I started working with my coach Ivan Lendl the first time around, I definitely tried to play more aggressively, whether that meant hitting the ball harder or standing inside the baseline.

I would have been 24 at the time, so I was still fairly young, trying to improve and play more offensively in the bigger matches.

It didn't stop when Ivan left in 2014, though. I was still trying to play positive tennis when I started working with Amelie Mauresmo, but also to add new dimensions to my game.

It's all about picking the moments when you're going to go big or play with a little bit more variety.

I've had better results on clay over the last couple of years and that isn't because I was hitting the ball harder, it's because I was playing smarter and more intelligent tennis.

If my forehand speed dipped for a while, it might also have had something to do with returning after my back surgery in 2014.

I had lost a little bit of pace and power during that first six to nine months, and with that I lost a bit of confidence.

Obviously when I was working with Ivan the last time that wasn't the case. I was extremely confident because I was winning a lot, beating the best players and winning big competitions.

'Suddenly I had to sit back down'

Following a match like the one between Roger Federer and Marin Cilic on Wednesday can be hard and you kind of have to be ready the whole time.

For the first couple of sets I'll be up in the locker room and usually start seeing my physio halfway through the first set for 35 or 40 minutes.

When I'm finished with him, after two sets I'll head down to the gym. Then, as it starts to get towards the middle part of that set, I'll start warming up. That's the theory anyway.

Wednesday was quite a difficult one to judge. It looked like Cilic was going to win at 3-3, 0-40, in the third set but then suddenly I had to sit back down and start again.

By the fourth set we just didn't know because Cilic had a match point. And from then until when the tie-break finished can be 25 minutes - and you're going on five minutes after they shake hands.

'It's your job to bring the energy'

It's not just the fans, players get nervous watching matches in the locker room, too, because you can see the atmosphere and feel the tension of the big points, so sometimes you have to settle yourself down a bit.

I was aware heading out that Centre Court wasn't going to be full after such a long match but the crowd filled up fairly quickly, and it's kind of your job to bring the energy.

If I seemed pumped up against Jo-Wilfried Tsonga, I wasn't especially trying to get the crowd going at the beginning of the match, it was more to get myself going.

There are enough nerves at the start of a Grand Slam quarter-final, especially if you've been waiting around and watching a match like Roger against Marin.

Regardless of whether there are a lot of people in there at the beginning of the match, crowds are not as engaged as they will be at the end of a set.

That's totally normal and it's up to you to try and make sure you get off to a good start.

'Berdych hits a big ball'

Playing with the kind of variety I talked about doesn't work against everyone, but against Tomas Berdych it has worked well over the last couple of years.

He hits a big ball and likes to dictate, so I need to make sure I keep him on the back foot as much as possible in Friday's semi-final.

We haven't played on grass before so I'll have a look at a couple of his matches over the last week and make a plan.

Having a rest day on Thursday will help me recover from playing five sets and I'll be ready to go on Friday, whether I play first or second.

Andy Murray was talking to BBC Sport's Piers Newbery.