Can you forgo your readied action to take an opportunity attack instead? [duplicate]

Question

Example:

• Player 1 uses the ready action to do something when something happens (unimportant)
• Goblin, decides to charge across the battlefield and attack Player 2, but happens to cross paths with Player 1 possibly provoking an opportunity attack (here lies my question)

Could Player 1 decide to ignore their readied action and use their reaction to attack the goblin? This would of course take up their reaction so they could no longer take their readied action when it triggers.

If so; let's say it is a fireball that was readied (or any spell), would Player 1 be required to drop the fireball spell? They technically cast it as part of their ready action, but I would understand if this would be a downside to using a reaction before their readied action triggered (maybe this should be another question, but please answer it anyway and tell me if I need to create a separate one so you can answer it there too :P).

Answer 1

Yes

Nothing in the ready or opportunity attack rules suggest that they're mutually exclusive beyond using one's reaction, which is only used when actually making the opportunity attack or taking the readied action. Therefore, you can forgo the option to use the readied fireball to make an opportunity attack if you wish and circumstances permit.

Using one's reaction on the opportunity attack consumes their reaction until their next turn, so the readied action cannot be taken. For readied spells, the character won't regain the spell slot spent and can technically keep maintaining concentration on the readied spell, although they won't be able to actually fire it without an unspent reaction. Any readied actions that haven't been taken cannot be kept readied further than the beginning of the character's next turn as explained in the Player's Handbook Errata:

Ready (p. 193). You have until the start of your next turn to use a readied action

Therefore, in practice, a character forfeits their readied action when making an opportunity attack, unless they have a feature that allows them to make an opportunity attack without using their reaction (such as the Tunnel Fighter fighting style from the Underdark UA).