Ahead of Tottenham's Champions League opener with Villarreal, Romero was asked if the Inter Miami star will be ready for the World Cup next year.
Romero replied: "I can answer about Leo, I think he’s fit, I think he could easily take part. It’s his decision. We all enjoy playing with him, we all enjoy watching him play. For me, and for people who know about football, I think he’s the biggest player in history.
"I love having him as a team-mate in the dressing room and sharing moments with him. We've had some very happy times together. Of course, I think he's going to be right for the World Cup. Of course he is.
"As for the rest and the season, I think I go by day-to-day. Tomorrow we have a massive game, a very key game for us. My head's focused on that game.
"When I'm with the national team, it's still a long time before we start thinking about the World Cup. Lots of months ahead before that comes into the frame. It's all about concentrating on Tottenham and the game tomorrow. We've really got to get a win tomorrow night. That's very key."