Novak Djokovic advanced through his quarterfinal match the easy way when Fabio Fognini was forced to withdraw with an injury. 
I’ve read some speculation on whether it is good or bad for Novak to get a freebie in the middle of the tournament. Example: “Will four days off throw off his rhythm?” I thought I’d weigh in since I experienced something similar in the Australian Open one time and lived to tell the tale. And let me say unequivocally that as far as I am concerned there is nothing bad about this situation for Novak. He’s healthy, fresh and into the semis. 
It was 1992 and it was a Friday. I was into the semis of the Aussie Open set to play Richard Krajicek. I showed up early in the day for my match as per normal to get a warm up in with my coach Brad Stine, eat a bit and get myself ready for the battle ahead. I had warmed up, showered, eaten and was now in the locker room about an hour before match time when Brad and I started noticing officials going into the trainers room with unusual frequency. Something odd was happening…was Richard hurt? Sure enough the referee walked out and directly to where we were sitting and said it looked like Richard was going to be unable to play (due to a shoulder injury he sustained in a 5 set win over Michael Stich in the qtrs). A few minutes later Richard came out of the training room and over to shake my hand and confirm it. I shook his hand with a somber and apologetic look…and I was bummed out for him to have to default but I also was overjoyed to be in the finals. It was a weird feeling but that is the tennis landscape…you’re all fighting for the same prize and only one gets to move on and this time it would be me. 
So I faced the situation that Novak is now facing; how do you keep your match rhythm without a match? I had played a few days prior and won easily (over Amos Mansdorf in 3 quick sets) so I was not in need of rest and I wanted to keep my good rhythm going without taking anything out of the tank. Should I take the rest of the day off? No, I was way too amped up for that and like a horse that needs to run hard every now and then I needed to go out and get a hard hit in otherwise I would probably go crazy mentally. I needed to blow off some steam. So Brad and I decided I needed to go play at least 1 hard set, if not two (but not five), just to give my body what it was anticipating and keep it fine tuned. So he went off in search of a junior for me to beat up on, since no one else was around other than Edberg and Ferreira, who were playing in the other semi and I went over to the media center to make the rounds for written and TV PRESS TO tell them how conflicted I was at winning by walkover. Yes, I played the part and said most of the right things about how sorry I was not to be able to play the semi. I lied a little…sue me.
After I was done stretching the truth with the media I gathered my sticks and headed out to court 2 with the junior (can’t recall his name) and played a hard set and then had Brad drill me a little bit after. I was on the court about 90 minutes, which is about the time of my match with Mansdorf. Then Brad and I went for our normal cool down run by the Yarra, followed by a stretching session and massage. In other words, exactly what we normally did with a match simulation. The only thing I didn’t have that day was the mental stress of taking out a tough opponent. It was just about a perfect day. The only thing I missed was the incredible rush after winning match point you always get when you win, but that was a fair (and rare) trade I was willing to take. 
I did wonder in the back of mind how not playing a match for a few days might affect me in the beginning of my match with Edberg in the finals. In the end, not at all. I had a normal light day of practice on Saturday and by the time I went onto the court for the Sunday final I felt very settled and concentrated with the normal accompanying anxiety (this was my 3rd Major final). I played well and toughed Stefan out in 4 sets. I didn’t thank Richard in my acceptance speech but I probably should have since he could have not only beaten me but also taken my legs out with a long match even if I had won…that’s why you never look a gift horse in the mouth as a tennis player.  Not only the risk of losing that match but also there’s the risk of losing the next match via fatigue. 

I’m not sure what Novak’s typical routine is but I would guess he had a vigorous practice on Tuesday. And I would imagine he is so confident right now that nothing would bother him too much; certainly not an extra day of rest. With his current form he didn’t need a gift horse but one of life’s ironies is that the more you have, the more you are given…here’s another example. But with Roger awaiting in the semis and likely Rafa in the finals there will be no more gifts. He’ll have to earn it the hard way.