A rematch between Andy Ruiz Jr. and Anthony Joshua is in fact happening next, according to Eddie Hearn.
The British promoter announced on Twitter that he has triggered a rematch clause and is planning to have the rematch for the WBA, WBO and IBF heavyweight titles either in November and December. The venue has not been decided and is set "to be confirmed shortly."
After meetings with AJ, Rob Mc and the management team in NY, we have today triggered the contracted rematch clause with Andy Ruiz Jnr. The fight will take place in Nov/Dec at a venue to be confirmed shortly.— Eddie Hearn (@EddieHearn) June 4, 2019
The announcement comes three days after Ruiz scored a major upset win over Joshua to win the unified heavyweight titles. Ruiz dropped Joshua twice in the third round and then twice more in the seventh round to stop him. The fight headlined the June 1 Matchroom Boxing card that was streamed on DAZN and took place at Madison Square Garden.
Ruiz got the opportunity to fight for the unified heavyweight titles after Jarrell Miller, Joshua's original opponent, failed multiple drug tests back in March and was denied a license to fight the heavyweight titles. Ruiz became the first male Mexican heavyweight champion when he defeated Joshua. The win pushed Ruiz all the way to the top three on Fightful's boxing rankings at heavyweight, which can be seen at this link.
Fightful did a post-show podcast dissecting the first fight between the two as well as the rest of the card, which can be seen in the video below.