Shannon accepted an offer to work in Greece in 1971, where he coached PAOK to fifth in Alpha Ethniki in 1971–72. He also led the club to victory in the Greek Cup in 1972 with a 2–1 win over Panathinaikos at the Karaiskakis Stadium; Giorgos Koudas scored both goals. He then took the club to second place in 1972–73, just two points behind rivals Olympiacos. They also had to settle for second place in the Greek Cup, as they lost 1–0 to Olympiacos in the final. In the European Cup-Winners' Cup they reached the quarter-finals, bowing out to Italian giants AC Milan. He departed the Toumba Stadium following a fourth-place finish in 1973–74. Before leaving he guided the club to another Greek Cup title, as they beat Olympiacos on penalties.