The T-shirt on sale at Doha's main market declares "Our blood is Arab", and that is the mood buoying Morocco as it prepares to become on Saturday the first Arab nation to play a World Cup quarter-final.Regional rivalries are being forgotten. Morocco's red flag with a green star is becoming a best-seller seen across Doha ahead of their clash with Portugal.The flag -- along with those of Qatar, Tunisia and Saudi Arabia -- features on the "Our blood is Arab" T-shirt selling at Doha's Souq Waqif market.