Critics may have scoffed when Bellator put together its fight card headlined by two old men in Kimbo Slice and Ken Shamrock, but the fight promotion is laughing all the way to the bank as the event broke its all-time viewership record.

Bellator 138 got 1.58 million viewers on average for the three-hour show, with the highest quarter hour in the main event doing 2.1 million viewers. As noted by MMAFighting.com, Spike was almost the highest rated cable network in Adults 18-49 during the three hours the show aired, doubling FOX's coverage of the U.S. Open Golf Tournament in the same time slot.

The numbers smashed the previous Bellator record by 27 percent, beating the old record of 1.24 viewers on average during their Nov. 15 show featuring Tito Ortiz and Stephan Bonnar, which had a peak of 1.84 million viewers during the main event.

As pointed out by MMAFighting, the numbers are doubly impressive considering the promotion put on the event on a Friday, which is not historically a great time slot for combat fighting.

Bellator 138 also got the second-highest numbers of 2015 on cable, beating every UFC event except for the FOX Sports 1 broadcast of the fight between Conor McGregor and Dennis Siver, which got 2.75 million viewers.

Slice escaped a rear naked choke to knockout the 51-year-old Shamrock in a fight that lasted just 2:22 in the very first round. Some corners have voiced that the fight looked fix, but that apparently didn't dissuade the viewers from tuning in.

"The fight looked fake as f**k," UFC analyst Joe Rogan said on his podcast. "When Ken did take [Slice] down, he never hit him once. How about that? He never hit him. He had him down. He had him flattened out. He's not blasting him with punches. He's got him flattened out and he's not hitting him. That doesn't make any sense."