Brazilian football (soccer) star Ronaldo continues to struggle in his comeback from two successive knee surgeries.

After several strong appearances in Italy, Ronaldo limped off the field Sunday with yet another leg muscle strain. Ronaldo looked strong through the first half of a 3-2 Internazionale win over Piacenza, including a move in the 43rd minute that drew the opposing goalkeeper's ejection and a penalty shot converted by Inter teammate Christian Vieri. But the 25-year-old limped off the field midway through the second half, as he has on two previous occasions, since making his return to competition in late September. Inter team doctor Franco Combi said the injury was an aggravation of a left thigh muscle strain suffered last month against Lecce. A similar light strain had also forced Ronaldo to stop after a brief appearance in a UEFA Cup match right after his return to action.

The star is hoping to play for the Brazilian national team at the World Cup in June. The two-time FIFA player of the year had looked strong in his appearances over the past month, including a pair of goals on Wednesday in a win over Verona.