BIRMINGHAM, England (AP) -- Mark Munoz stopped fellow American middleweight Chris Leben at the end of the second round in the main event in UFC 138 on Saturday night at LG Arena. After the fighters exchanged takedowns in an even first round, Leben's left eye was badly cut in the second, prompting referee Marc Goddard to have the injury checked by a ringside physician. Getting the all-clear to continue, the round resumed with Leben still competitive. After the pair broke up after the second round, though, Leben's corner asked for the fight to be stopped. "It takes a man to know when they're beaten, and I was beaten tonight," Leben said. "My hat's off to Mark Munoz." Both men weighed in at 186 pounds. Earlier, Renan Barao beat English fighter Brad Pickett on a rear-naked choke submission at 4:09. Barao weighed in at 136 pounds, two pounds heavier than Pickett.