Spot the mistake...

[Stickleback]

I think I need help…

Live £5 ($10) r&a tournament – 120 starters. Re-buys period ended 15 minutes ago.

7 players + big stack just moved to my immediate left, but sitting out this hand. Hero is CO with 1700 plus change. Blinds 50/100 and will rise to 100/200 in about 5 minutes. Players to hero’s left have been respecting his raises, B and BB both have hero covered. UTG +1 has hero covered and has been raising 50%+ hands including 3 of the last 4. He has called re-raises with J9s and A4o in the last 10 minutes or so.

UTG+1 raises to 400, Hero looks down at A8o and…er…calls! Duh!

I’m guessing no one calls here? But what action should hero have taken?

Steve