Wimbledon: Steve Johnson has the power to scare Roger Federer, says Nick Bollettieri

American is leading a renaissance of his compatriots and has the potential to give Swiss opponent a game on Monday

Steve Johnson has enjoyed an impressive Championships this year (Getty)

Holy mackerel, what a Wimbledon we’ve got on our hands. Part of me was very sorry to see Novak Djokovic lose to big Sam Querrey because the world No 1 is such a great champion, but his defeat has opened up so many possibilities in the top half of the draw.

Roger Federer is now the highest-ranked player in the top section. He hasn’t dropped a set in his first three matches, but I’m not sure how hard he has been pushed. He’ll certainly be in a battle on Monday against Steve Johnson, who is one of many Americans having a good Wimbledon.

At No 29 in the world Johnson is at his highest ever position in the rankings. He had won only one match in his three previous visits to Wimbledon but he’s in the fourth round after good wins over Jeremy Chardy and Grigor Dimitrov.

Johnson’s a bulldog. He’s a fighter. He doesn’t smile. He doesn’t care about anything apart from winning the match. When he’s out on the court it’s like he’s on a battlefield mission. He has a lot of guts. And he knocks the crap out of every ball.

Federer needs to use a little bit of this and a little bit of that to break up Johnson’s rhythm. He won’t want to get involved in a hitting contest with him. He mustn’t just try to hit through him, because that’s the sort of encountrer Johnson would love.

I’ve been very impressed with the accuracy of Federer’s serves. They hit their target with the accuracy of guided missiles. He’s consistently putting the ball on the right spot at the time. He needs to keep doing that, because if he can keep holding his serve I think he has the ammunition to break Johnson.

Kei Nishikori has a great chance of reaching the last eight when he faces Marin Cilic on Monday (Getty)

The next highest seed in the top half of the draw is Kei Nishikori, who has been with me at the IMG Academy in Florida since he was 14. He has excellent coaches in Dante Bottini and Michael Chang. Bottini has been with him for several years, while Chang has shown him how to fight and how to win.

Nishikori plays Marin Cilic in the fourth round and I see this as a great opportunity for him. They met at the US Open two years ago, when Cilic played the best semi-final (against Federer) and final (against Nishikori) that I’ve ever seen anyone play. Nishikori, who has won their two subsequent meetings, has improved a lot since then, while Cilic has never quite rediscovered the form he showed in New York.

Can Querrey carry on where left off when he faces Nicolas Mahut in the fourth round? What Big Sam needs to do is put aside all his thoughts about beating Djokovic. It can be difficult to back up a great win like that, but it’s history now. Sam just has to focus entirely on his next match. If he serves like he did against Djokovic and hits as many forehands then he has a great chance.

Coaching report

This is proving to be a great tournament for Americans. Holy cow, most of my fellow countrymen and women are usually on a plane home to the States by now. I can’t remember the last time there were as many around to celebrate the Fourth of July at the All England Club.

There are four American women through to the last 16 – Serena and Venus Williams, Madison Keys and Coco Vandeweghe – and I was particularly impressed with the way Vandeweghe beat Roberta Vinci in the first match on Centre Court on “People’s Sunday”.

I’ve known her coach, Craig Kardon, for a long time and he’s doing a great job with her. Nobody could question Vandeweghe’s great sporting background – her mother represented the US at both swimming and volleyball – but Craig has helped her to get the mental side of her game right as well.

She is also serving well, which can be so important on grass. That helped her to get to the quarter-finals at Wimbledon last year and she’s within one win of repeating that feat. She should fancy her chances against Anastasia Pavlyuchenkova in the fourth round.

My tip of the day

Each day this week I’m going to give you a little tip on how to improve your own game. You’ll find plenty more like this on my website: www.nickbollettieri.com.

Today’s tip: how to improve your chances of getting in the right position to play your next shot. The key is to keep your eye on the ball as your opponent hits it and to follow its flight. You need to be on the move before the ball even crosses the net, so it’s vital that you’re tracking it all the time, reading the flight and working out where it’s going to land. If you wait for the ball to come over the net – and worse still, if you wait for it to bounce – before getting in position, you won’t give yourself the chance to play your best shot.