It keeps the Blues within touching distance of early pacesetters Glentoran but for the Ports this second defeat in three outings perhaps presents a sizeable mountain to climb even at this early stage.

Thompson opened the scoring for Linfield after 27 minutes when he turned home a low header from a Paul McAreavey free-kick which Winkie Murphy knocked across the face of goal.

However Portadown levelled nine minutes from the break through Scottish marksman Gary McCutcheon after he made the most of a Kris Lindsay error to despatch a 12-yard effort past Alan Mannus.