Llorente put Atletico in front at the start of the second half, tearing into the box from the left wing and tucking the ball inside the near post from a tight angle.
Betis had played well in the first half and dominated the ball. However, Atletico took control of the game after Simeone hauled off Lucas Torreira and Thomas Lemar for Yannick Carrasco and Hector Herrera for the second period, instantly giving the team more pace and purpose in midfield.
The visitors were reduced to 10 men with 20 minutes remaining when Martin Montoya was sent off for hauling down Carrasco. The referee initially gave the defender a booking but changed it to a straight red card after a VAR review.