David James has the jersey at the moment but the 38-year-old's rivals are queueing up for when he hangs up his gloves, and there is talk of Arsenal's Spaniard Almunia throwing his hat in the ring.
Green has put forward a convincing case this season and earned his second cap in the clash against Spain in February, with his club manager tipping him to add to his appearances.
"He has been one of my key players, he has been great,'' Zola said. "He had a few problems at the beginning of the season but after that he has just changed and has been different class.
"I can say, if he plays for England, he's going to be a very good goalkeeper for England. He can be easily the number one, and that doesn't come because he is my goalkeeper - it's because I see he's very good. He gives you so much security.''
It has taken a while for Green to be called up by Capello, and Zola feels his goalkeeper has shown plenty of character to keep going when he was out of favour.
"He has had disappointments in the past internationally, not being selected for squads but he has never let his head drop, he has always been very positive, always kept his spirits up,'' Zola said.
"He is a strong man. He has got a strong personality, he doesn't let anybody let him down. It's a good point.''
Zola is confident that Green will follow the example of himself and assistant boss Steve Clarke by signing a new contract to stay at the club. The Hammers boss wants to keep the current squad together and add a few players over the summer.
"I don't think we need more than that, maybe two or three players that might be coming in,'' Zola said.
At the moment, Zola's target is getting the two wins and a draw that he feels should be enough to finish seventh in the Barclays Premier League and qualify for next season's Europa League - but he is wary of the trip to Stoke City this weekend as Tony Pulis' side have an impressive home record.
"I still believe 52 points will still make it, so we need seven more points out of four games,'' Zola said. "Stoke's home form has been the secret for their season, because they won only one game away from home.
"At home they are a different team; they are very, very dangerous, very difficult to beat, and I'm expecting a game like that on Saturday as well.''
"I know they are fighters,'' Zola said. "They really put a lot into the pitch.
"I've seen it (Fuller's red card) a few times on YouTube. Obviously it was a controversial situation and you don't want to see things like that happening, not even to the opposition.
"I believe that it's over, I think Tony Pulis has dealt with the situation very well and Fuller is back and doing very well for them.''