Fresh off his scintillating knockout over former UFC light heavyweight champion Lyoto Machida last month, rising middleweight contender Derek Brunson is hoping to land another former champion his next time out.

Brunson, who has finished all six of his victories since the start of 2015 by way of first-round knockout, is now taking aim at former UFC middleweight king Luke Rockhold. After Brunson hilariously compared Rockhold’s current win streak to excrement found in dirty underwear, the two battled it out via Twitter.

Here’s how it unfolded:

Rockhold, 33, is coming off a second-round submission win over David Branch this past September. The elite middleweight is still rebounding from losing his 185-pound strap to current UFC middleweight champion Michael Bisping in 2016, but remains one of the most sought after opponents in the weight class.

While other matchups exist in the division for Rockhold to take, including current interim middleweight champion Robert Whittaker and former title challenger Yoel Romero, a pairing with Brunson does make sense at this time. Not only has Brunson proven to be one of the best finishers in the middleweight division over the past few years, but both men are healthy and available for a booking.

And if Chris Weidman vs. Ronaldo Souza goes down later this year, Rockhold’s options for his next fight will become even more limited.