Ruud van Nistelrooy and Patrick Kluivert were born on 1 July 1976. Between them these two Dutch strikers spent almost 15 years at world football's top table, yet they never sat together. Van Nistelrooy's peak years began just as Kluivert's career started to fade away. Their shared birth date makes them the perfect example of the football Venn diagram that includes teen prodigies to the left and late bloomers to the right. The same phenomenon applied to the international careers of Roberto Mancini and Gianfranco Zola, who will meet again when Manchester City play Watford in the FA Cup third round on Saturday.

Mancini and Zola were part of Italy's golden age of fantasisti in the 1990s, with Roberto Baggio and a young Alessandro Del Piero also competing for one position. The stock phrase "embarrassment of riches" feels inadequate to describe such a pool of talent. You could find disciples of all four geniuses who would tell you their man is the greatest No10 of all time, never mind the best in Italy in the 90s. The competition was such that Mancini never played in a World Cup, and Zola managed only 13 minutes in 1994.

Although they were born only 18 months apart, their international careers had scarcely any overlap. Mancini made his debut seven years before Zola, and they were never on the field together for the Azzurri. The only time they played in the same game was in Germany in March 1994 – when Zola replaced Mancini at half-time. An angry Mancini told Arrigo Sacchi, the manager: "I'm finished, don't call me again." Sacchi did not. It was the last of Mancini's 36 caps; 30 of Zola's 35 caps would follow over the next three years.

"It was crazy," says Zola, holding court with his usual quiet charisma at Watford's training ground, of the competition for places. "He was a fantastic player, I was a good player as well, and there were others. It was not easy for Sacchi."

Zola and Mancini were players from the same pod: mischievous, imaginative, obscenely talented and as elusive as urchin pickpockets. They scored two of the most famous backheeled volleys of all time, Mancini for Lazio against Parma and Zola for Chelsea against Norwich City. Zola also recalls an astonishing volley from Mancini in 1990-91, when the future champions Sampdoria won 4-1 away to the defending champions, Zola's Napoli. "It was one of the best goals I've seen," says Zola. "He was a pain in the backside to be honest. He was so good, so intelligent, so talented. He and Luca [Vialli] were very, very competitive."

Despite Mancini's competitive nature, Zola did not think they would meet on the touchline. "I didn't expect him to go into management. I knew he was an intelligent player, and normally players like him interpret football in a way that you don't think they're going to go into management. He was a flair player, an imaginative player, and sometimes creative players like him don't become managers." The feeling, he suspects, is mutual. "You'd have to ask him, but I think he would be surprised that I became a manager, yes."

This will be their second meeting as managers. Zola's final game at West Ham United was against Mancini's Manchester City, and he gives the impression of a relationship that is perfectly civil but not close. If they met on even terms as players, they do not any more. City are one of the richest clubs in the world, Watford one of the poorest clubs in the Championship, with a squad that includes 10 loanees from Udinese.

"When you consider he has won the league and the FA Cup, I don't think he's done a bad job," says Zola. "But these are my parameters – I don't know what the owners or the supporters think. He certainly hasn't done too bad. But I don't find it strange that he is under pressure. He's managing a team that cost more than £300m. When you invest so much money you believe you have to achieve everything straight away, which in football doesn't happen, especially in a league like the Premier League. That is what, in my opinion, makes his job even more difficult than the others."

There is one other thing that makes his job more difficult: Mario Balotelli. Zola says managing Balotelli would be "a good challenge", although that was before Thursday's remarkable training-ground confrontation with Mancini. "He's got unbelievable quality. The challenge would be to try to make him a little bit more reliable. Balotelli sometimes does things that seem strange or unbelievable to most eyes. But maybe for him they are normal; maybe he isn't trying to upset people."

Handling Balotelli is a challenge for Mancini but Zola thinks the day-to-day minutiae of life in England has also furthered the City manager's education. "I've always said that coming to play here was a great thing for my game, because I improved my qualities. I believe it's also great for us as managers. I don't think Mancini is coaching the team in the same way he did at Inter, that's for sure. The English mentality has helped him to be a better manager."

And to appreciate the value of the FA Cup. It was Mancini's first trophy in English football two years ago, and Zola's first as a player, in 1997. "This is, in my opinion, one of the best competitions in the world," says Zola. His side will meet perhaps the best team in that competition. "We are playing against the champions of England, so theoretically it should be the hardest task. They are out of the Champions League so they will consider this a priority. It's not going to be easy, that's for sure. If we only try to stop them playing, we're just going there for the beating. We have to go there and play our game, like we normally do. We will have a proper go."

Zola has a dangerous pool of attacking talent, including Matej Vydra, the Czech Republic international; Fernando Forestieri, Alex Geijo and Troy Deeney. Which strikers will he play? "Maybe four?" he teases. "No, that would be too much. I've got a few options, which is good. I know they are the champions and we are a Championship team," says Zola, lowering and slowing his voice mischievously, "but I think we can maybe cause something. A little troubles. Here and there."

If they win, Zola might break the habit of a lifetime. "I'll get drunk, that's for sure. No, I'm only joking. It would be a great thing for the club, for the supporters and above all for the players. It will be a great education for us. In my opinion we have won already. I'm really looking forward to seeing my team play against a good team. I want them to see how good players play on the pitch. I believe Manchester City will have to play a good game if they want to beat us."

At the end he will go to Mancini's office to discuss the game and maybe kick around old times. "I'll be delighted to have a glass of wine, depending on the result. I'm sure he's got a good wine." A vintage from the mid-90s would not be inappropriate.