Defending champion Olympiakos overcame host Xanthi last night to advance to the Greek Cup’s semifinals following a goal from a free kick by Brazilian Rivaldo, his third successful strike in seven days. Rivaldo, whose goal in the 75th minute gave Olympiakos a 1-0 victory at Xanthi for a 2-1 aggregate, had also scored with a free kick in last week’s 1-1 draw between the two clubs in their quarterfinal cup encounter’s first leg. Earlier this week, in a league match against Kallithea, Rivaldo opened the scoring for Olympiakos with a free kick for an eventual 2-1 win. Olympiakos, currently on track for a repeat of last season’s league-and-cup double triumph, will now meet Larissa in a home-and-away encounter for a place in the final. In the other semifinal, surprise qualifier Agrotikos Asteras, from the third division, will meet either second-division club Niki Volos or AEK. The semifinalists, locked at 0-0, are scheduled to play their second leg on February 22. The tie has been delayed by weather-related poor pitch conditions.