In a UEFA Cup match against Newcastle United on 8 March 2007, Grétar scored in a 4–2 loss. After the match, Grétar said that AZ would score two goals in the next leg, a prediction that he made turned out to be correct, as AZ went on to win 2–0 and subsequently saw the club go through to the next round. After being out of the first team over suspension, Grétar was featured in the KNVB Cup Final against Ajax, playing 120 minutes and scored in the penalty–shootout, as AZ went on to lose 8–7 as a result.
In a UEFA Cup match against Newcastle United on March 8, 2007, Grétar scored for AZ, who lost 4-2. After the game, he predicted that AZ would score two goals in the next leg, which turned out to be correct as they won 2-0 and advanced to the next round. Following a suspension, Grétar played in the KNVB Cup Final against Ajax, playing for 120 minutes and scoring in the penalty shootout, but AZ lost 8-7.