DOHA: Former champions Al Gharafa on Friday beat Mesaimeer 1-0 to reach the semi-finals of the Emir Cup.   Al Gharafa are now the third side to reach the last-four following the wins by Al Sadd and Al Duhail on Thursday.   After a goalless first half, in which both teams produced quality moves, Al Gharafa nudged ahead with a snap-header by Ahmed Alaeldin in the 88th minute.   After receiving a high cross from the flank, Alaeldin jumped at least 3 feet in the air to deflect the ball into the net at Al Arabi Stadium.   Mesaimeer goalkeeper Mohammed Ghanem also lunged at the ball and in the process ended up hitting Alaeldin on the neck.   "I am very happy with this performance. It was a tough match. But we are happy we got that late goal," Alaeldin said after the match.   Al Gharafa will play the winner from the Al Rayyan-Al Arabi clash later in the day.