Nick Bollettieri's Wimbledon Dossier: Lopez shows the value of a dangerous leftie

While Ancic paid for losing his cool, Pierce won her just rewards by listening to me and hitting the cover off the ball

Feliciano Lopez can be as dangerous as hell, as he showed yesterday when beating Mario Ancic in straight sets. Lopez is a leftie. His serving was superb, as was his volleying. He can play anywhere on the court, and, most significant of all against Ancic, he kept his cool. Ancic didn't, and that was part of the story of his defeat.

His serve, one of his big weapons, wasn't working. He couldn't return the ball consistently. And when, after he was broken in the first game of the second set, he tried to smash up his racket in frustration. He got himself a code violation. He might as well have hung up the white flag. Losing it like that is not Ancic's style, and he sent a powerful message to Lopez that he was seriously flustered. Bad move. That boosted his opponent, allowing Lopez to feel even better than he already was.

Great sportsmen either keep cool, or know exactly how to channel their rage. Michael Jordan was the coolest of cats. He could lose five three-point shots in a row but you wouldn't know from his face that he hadn't got them. John McEnroe and Jimmy Connors could appear to lose it totally, ripping up the umpires, arguing over line calls, going crazy. Those guys should've won Oscars. They knew exactly what they were doing. They were in control, pumping themselves up. And of course they had the enormous talent to back up the shouting.

Mary Pierce's win yesterday over Flavia Pennetta underlined the importance and value of entering a match with the right attitude, and conveying it to your opponent. In Mary's case, she let the Italian girl know right from the start that she was intent on smashing her off the court. She set up the game point in the first game with a huge drive and then served so big that Pennetta could do nothing with it.

I've been working as part of Mary's team again for the past few months and we keep the same routine for my pre-match advice. We go over it on the phone, at 11pm. That time works for Mary because she goes to bed and she can sleep on it.

We keep it simple. For her third-round match against Ana Ivanovic, it was: "Beat the crap out of the ball. Don't let Ivanovic get a grip." That worked fine. For yesterday's match, it was: 'The balls are starting to bounce higher, to your shoulder. That suits you. You can do serious damage in these conditions. Whack the hell out of that ball. And whack Pennetta. Don't let her breathe out there. Take control from the start and keep it."

I'm also using the reward system. Mary needs to be careful what she eats but her favourite food is tiramisu. She earned two mouthfuls yesterday. She laughs her head off at me when I give permission. She's happy. She's been in control on court. She's shown her opponents that. The key now is maintaining it.