DOHA: Former champions Al Rayyan on Friday beat hosts Al Arabi 3-0 to seal their place in the Emir Cup semi-finals.   Playing at Grand Hamad Stadium, Mohsine Moutaouali (53), Rodrigo Tabata (82) and Aldoukali Al-Baoure (90 +4) scored the goals for Al Rayyan, coached by Michael Laudrup.   After a goalless first half, Moutaouali opened the scoring with a snap-header in the 53rd minute on a loopy cross by Tabata.   In the 82nd minute, Moutaouali ran with the ball for almost 40 yards before clipping a neat cross for Tabata who was stationed inside the Al Arabi box.   Tabata picked up the ball before curling a left-footed shot the right of goalkeeper Masoud Zarayi.   In injury time, Aldoukali curled in a spectacular shot 30 yards away from the goal for Al Rayyab's third strike.   Al Rayyan will now play with Al Gharafa in the semi-finals of Qatar's most popular football tournament.   Earlier on Friday at the same venue, Al Gharafa edged past Mesaimeer 1-0.   The semi-finals will be played on May 11 and 12 at Jassim bin Hamad Stadium.   The final of the tournament will be played on May 19 at the Khalifa International Stadium.