BBC Sport NI's Mark Sidebottom surveys the Estadio do Dragao in Porto where Northern Ireland will face the might of Ronaldo and his Portuguese team-mates.
BBC Radio Ulster will have live coverage of the Group F qualifier while there will also be commentary on the BBC Sport website.
Cristiano Ronaldo is set to win his 100th international cap in the game against the injury-hit Northern Irish.
WORLD CUP QUALIFIER GROUP F: PORTUGAL V N IRELAND
Venue: Estadio do Dragao, PortoDate: Tuesday, 16 OctoberKick-off: 20:45 BST
Coverage: Live on BBC Radio Ulster and commentary on BBC Sport website