(Adds next opponent)
By Clare Lovell
LONDON, June 28 (Reuters) - Rafael Nadal believes the best example his successful generation have offered up-and-coming tennis players is that they never stop battling to beat each other but remain friends off the court.
The world number one showed his fighting qualities again on Saturday when he lost the first set to unheralded Kazakh Mikhail Kukushkin before storming back to win 6-7 (4) 6-1 6-1 6-1 and land a place in Wimbledon's fourth round.
It was the third time in the tournament the French Open champion had staged a fightback while struggling to find his rhythm and footing on grass after the long claycourt season.
"I think it's a good example for the kids, the motivation and passion for the game," the Spaniard told reporters.
"I don't know how many times I've played against Novak, Roger, Andy...a lot of times.
"We only meet each other in semi-finals or finals. That shows we have been in that position a lot of times. That's very difficult mentally and physically," Nadal said.
"The example is we are fighters...for every single tournament. We are fighting for the whole year, another year, another year."
Nadal, aiming for his 15th grand slam title, said the four remained on good terms despite the pressure of competing under extreme pressure for big prizes.
"We are in the locker room, we still talk to each other. We have a very good relationship," he added.
"That's important because at the end tennis is only a game. The relationships are in my opinion more important than a game."
With heavy rain falling on Saturday, Nadal played under the roof on Centre Court and said the conditions were a little different.
"When you play indoors on humid days the court is a little bit more slippery. that makes the match a little bit different," explained Nadal.
He added that although he preferred to be outside he felt he played well - improving on his first two rounds.
"The feeling was great. I played aggressive. I had great movement, some from difficult positions," he said.
Nadal meets Australian wildcard Nick Kyrgios in the fourth round. (Editing by Tony Jimenez)