Can you win a game of chess against a Wizard?

Can you beat an Ogre at arm wrestling?

It’s time for an Opposed Ability Check. First, the Game Master declares the need for a check. Then, both the player and their opponent roll a 20-sided die. The Game Master chooses the ability (or reads it in the adventure text) then tells the player which ability bonus to add. The higher score wins!

Having a proficiency in the appropriate ability will give the player a bonus. 

A player will use their ability bonus to add to the roll, unless they have an appropriate skill, then they will use that bonus instead. Use your CHARISMA (or Persuasion if you have that skill) to convince a shopkeeper to sell you something for cheap. 

Use your DEXTERITY (or Stealth if you have that skill) to sneak past a snoozing bugbear.