The Penrith Panthers might have been able to build a substantial lead during the first half of the NRL season opener against the Manly Sea Eagles, but it could have been a lot more.

Penrith spent most of the first half on the attack, but the defending premiers were left frustrated after both of their first two tries were disallowed by the bunker.

Both Stephen Crichton and Brian To'o thought they had tries, only for them to be ruled out.

Crichton's first try - on the right-hand side of the park in just the fifth minute of the game - saw Liam Martin run into the line as a decoy runner, taking Kieran Foran out of any ability to be able to complete a tackle.

The fans were less than impressed with the opening decision of the game, but weren't about to be made any happier, with Brian To'o putting on a miraculous effort complete with numerous tackle breaks, only to be stopped by the bunker.

The ruling came as Jarome Luai got caught in the line desperately attempting to get out of the way following the gun winger cutting back in off the touchline.

Debatable as it was, Tom Trbojevic was the man impeded according to the bunker, with the Panthers held to zero.

The Sea Eagles scramble defence - which stopped Manly time and time again - could only go so far though, with the Panthers eventually getting the opening points thanks to youngster Izack Tago on the left.

Stephen Crichton would get his name onto the scoresheet after being denied 11 minutes before halftime, with Penrith going up 12 points to nothing shortly before halftime.