AMSTERDAM, April 20 (Reuters) - Ajax Amsterdam beat Feyenoord 3-0 in their Dutch league playoff semi-final first leg clash on Thursday.
The winner of the post-season playoffs, involving the teams who finished second down to fifth, secure a Champions League third qualifying round ticket.
In the other first leg semi-final, Groningen scored a 3-1 home win over AZ Alkmaar, who were second in the regular season.
Mauro Rosales opened the scoring for Ajax after 26 minutes and Feyenoord's Bahia was sent off on the hour after a second booking.
Ten minutes later Ajax midfielder Steven Pienaar was dismissed for kicking Dirk Kuijt but Ajax struck twice in 60 seconds through John Heitinga and Klaas-Jan Huntelaar.
Three minutes from time Feyenoord winger Romeo Castelen was also sent off, reducing his side to nine men.
The second legs are on Sunday. PSV Eindhoven retained the Dutch title earlier this month.