left knee injury could keep Italy forward Christian Vieri out of the World Cup, according to reports Tuesday.

Vieri was injured playing for Monaco in the French league Sunday and underwent medical tests in Italy on Tuesday, according to the Gazzetta dello Sport.

Vieri moved from AC Milan to Monaco in January to gain more playing time, with the aim of making Italy's World Cup roster.

On Feb. 28, Vieri hurt his left ankle while training with Italy and missed the Azzurri's friendly with Germany the next day.

On Sunday, he returned to Monaco's starting lineup but was replaced in the eighth minute after a hard tackle by Paris Saint-Germain's Bernard Mendy.

If Vieri does not return in time for the June 9-July 9 World Cup, Italy coach Marcello Lippi could recall in-form Filippo Inzaghi or Antonio Cassano, who has rarely played lately for Real Madrid.

Playmaker Francesco Totti's recovery from surgery on his left leg is on schedule and he is expected to be fit for the tournament in Germany.