Whether or not Rafael Nadal extends his mastery of red clay to 73 consecutive matches at the BNL d’Italia Masters Series tournament here today, there are many things of which you can be certain. He will put his shoes on properly, he will not throw his racket, he will not harangue his opponent, he will respect the umpire and his face will bear no trace of a scowl, win or lose.

Yes, he will keep his opponent – Daniele Bracciali, of Italy, is next in the eye of the storm – waiting at the net while he sips on his prematch drink, he will bounce up and down during the coin-toss, he will zigzag his way back to the baseline and will strike the ball during the warm-up almost as hard as he will when the match starts. Oh yes, he will definitely pick at his pants before and after – one of these days he will try it during – each point.

But of the many things that commend the performances of Nadal, the world No 2, there are many more that speak highly of his development as a man. In the stands at the Foro Italico today, as watchful as he has been in the 16 years he has coached his prodigious nephew, will be Toni Nadal.

For all the horror stories of tennis relatives who ought to have played no part in the sport, that of the Nadals is an object lesson in familial harmony. It might appear too cosy to some and yet Toni, 47, confesses to being a “difficult coach”. He played in the second division of the Spanish football league, passing his coaching badge 27 years ago, one of his four brothers, Miguel Ángel, was the famed “Beast of Barcelona”, the rock of Spain’s defence in three World Cup finals and another, Sebastian, fathered a boy 20 years ago who has become the pride of his nation.

Since Toni, who has coached Rafael since he was 4, persuaded his right-handed protégé to switch from a double-handed stroke on both flanks at the age of 10, the world No 2 has felt more at ease playing left-handed. Toni has been there all the way, as guide and mentor.

“He was always a very good pupil, because he was disciplined, I did not have to demand that,” Toni said. “We have a relationship that is different to other players because I can talk about behaviour in a way that someone else could not tell him. The people look at him and see a guy who always plays with a big illusion [light]. Before he played, I saw on television so many players who went out with a bad face. I detested that. Rafael wants to win but he wins with good manners.

“I said to him from the time he was very young ‘Rafael, you must play always with a good face. It is impossible to learn with a bad face.’ I say to my own kids [Toni has children aged 3, 4 and 5], long faces are not for us, there are people in Africa who have big problems. We don’t have problems, or if we do, they are only little ones.

“I say to Rafael sometimes when he misses a shot and has a long face – ‘You are not too good yet, you must still learn, the ball has gone out, it is only one thing.’

“Rafael has never thrown his racket. For me it is unbelievable how some people treat what they are given. He has never trodden the backs of his shoes, he gets them for nothing and yet for other people, they cost €100 [about £70]. There are players who have their rackets strung, they don’t use the racket and they go back the next day to have them strung again. That is bad.”

Could he ever see the time when he and Rafael might go their separate ways? “I would not want to coach anyone else,” he said. “I don’t need to work, for me it is good just to be behind this boy, he is as much my son as he is my nephew. I would not want to carry the rackets of anyone else.”

Unlike those who feel his physical style cannot be sustained deep into his twenties, Toni has a different view. “He needed that aggression when he was 17, 18, but we have changed some things,” he said. “I have told him, he cannot be the No 2 player and run more than the No 15, No 25, or No 50 player. Against the No 5, that’s OK and against [Roger] Federer, that’s normal, because he is too good. Rafael is learning all the time.”