Betting on the river is a unique round. Before this round, players had the opportunity to improve his hand. Once you reach the river, the bets here are just bluffs or value bets. You cannot knock a player out and you cannot semi-bluff. For this article we focus on how betting goes when you are on a heads up and when you are playing as the aggressor.
So what do you do if you have a top pair on a heads up and you form a scary hand on the river?
What you need to do will really depend on your position. In case you have a better position that your opponent like you are at the button and the other player is in mid-position. When your opponent checks and you are considering of making a value bet but you are worried of a check-raise. If the other player will always raise when you are beat and will call in case you get a better position then you will have a 2 of 3 chance of winning to make a bet. You have one chance of winning if you have a better hand and two chances of losing to bet if he has better cards.
The situation will be different if your opponent just calls and not raise even if he has a better hand. And there will be instances where you will be raised even when he has a better hand. These requires your judgment call since it differs in every situation.
If you have an early position and reach the river, you must be willing to bet since even if your opponent has a good hand, he will bet or will raise you. This way you will only lose one more bet by initiating the betting.
If your opponent has a semi strong cards, he will not raise you. Show some strength when you bet. He will hesitate to raise in fear of a re-raise. When you check, he will feel your weakness and grab the opportunity to make the bet. In this scenario your initial bet does not matter since you will be losing one bet whether you check or bet.