Nick Bollettieri: 'My verdict... Darn good. I would rate the girls as up there with the best of their age'

Potential. It's always the caveat with any young player. It has to be because nobody can ever predict the many circumstances that change. But I have absolute confidence that these girls have the ingredients. I was actually taken aback by aspects of what I saw during their stay, as I think they were sometimes, like seeing me on court for 14 hours a day!

Parts of their game were absolutely phenomenal. I would rate them in their age group as up there with 99.9 per cent of the best players of their age.

They came, with their LTA coach and their mother, with open minds. I believe it was a positive experience all round. My message is they have all their fundamentals on track: grips, technique, attitude, work ethic. They showed guts in tough sessions. They were all business on court. And their footwork was impeccable. Jessica was dynamite on her feet, and in one particular match, against a very good young player who did well in the recent Eddie Herr international tournament for the world's top youngsters, I was also impressed with her determination and focus. She won that match and I'd say that if Jennifer and Jessica had played in the 12-year-old event at the Eddie Herr, which took place before they arrived, they would have made semi-finals, at least.

The Eddie Herr 16s (for 16 and unders) was won by one of my students, Michelle Larcher de Brito, who is 12, while the Ren sisters' event at the Orange Bowl, currently under way, began with Hanna Orlik of Belarus, who is also 12 and won at Eddie Herr, as a red-hot favourite. But I was pleased with what they did during their visit. They have real potential.

I was delighted to provide the girls with a taste of my academy, and hope they can take something positive back. Equally, I'm ready and willing to come to England if there's anything I can do for British tennis.