Porto club defender Paulo Assuncao injured his right knee ligaments in the 1-1 draw with Lisbon's Benfica on Saturday and will be out of action for a couple of weeks.
The 27-year-old Brazilian legionnaire, who continued playing until the end of the match despite suffering the injury in the middle of the second half, learned after tests on Monday that he will be unable to play for at least two weeks.
A former player of Palmeiras and Nacional clubs, who spent the 2004-2005 season on loan at Greek Athens' AEK team, Assuncao has played 20 games this season wearing Porto's jersey.
Managed by Jesualdo Ferreira, Porto's team remains the leader in the Portuguese championship after the 23rd round and stays ahead of closest pursuer Benfica by one point.