Keeping up with the Kardashians season 18 just got more physical. The premiere of the reality TV show showed some clips where Kim and Kourtney appear to have a disagreement and turned into an actual fight later. 

Although fans of the show and the family have already seen the sisters get into verbal altercations many times, this is different. ET Online reports that the fight escalated into a full-on slap from Kim to Kourtney -- and this is just the first episode for the season!

The show premiered on Thursday night, moving from its original Sunday slot. So, how exactly did Kim and Kourtney end up fighting, and what else happened in the season premiere of Keeping up with the Kardashians season 18? 

E! Online reports that the fight started with Kourtney's reluctance and struggle to be back to film the reality TV show. Last year, she made a statement that she would like to take a step back from filming and let herself focus on being a mom to her three children -- Mason, Reign, and Penelope. 

She just came back from a long vacation in Italy and mentioned that she never wanted to film again with her sister Khloe. 

The big fight came at the end of the episode where Kim talked about her own work ethic and that of Khloe's, while seemingly throwing shade to Kourtney's. 

The latter is, of course, not pleased and things escalated to the point where even Khloe and Kendall had to intervene and break them apart. The season premiere ends with Kim slapping Kourtney. It seems that this latest season will give us more drama than usual. 

Meanwhile, the other events in the premiere include Kim actually looking like she'll be friends with Tristan. Even though Tristan and Khloe have broken up, Kim tried to make things less awkward by inviting him to dinner with her friends. 

While this made them closer, Khloe was quick to put a stop in the next scene by claiming that it was too soon for Kim to invite him to dinner in their own home as it was barely a year since the cheating scandal and their eventual separation. 

Also, in the episode is matriarch Kris, who panicked at Kylie being sick and not being able to attend the Paris Fashion Week. She was all set to do a big collab with Balmain and creative director Olivier Rousteing. But, with Kylie having strep throat, the big collab may not push through. The next episodes will show the aftermath of these events.