UFC on ESPN 39 carries a solid six-fight undercard slate for the Ultimate Fighting Championship’s brief return to the UFC Apex on Saturday in Las Vegas. The featured prelim is a crucial one: Former women’s strawweight contender Nina Nunes looks to start her journey at flyweight on a strong note, while Cynthia Calvillo tries to break a frustrating slide. Meanwhile, bantamweights should provide the best action. Ronnie Lawrence and Saidyokub Kakhramonov meet in a bout that should be much higher on the card, and “The Ultimate Fighter 29” winner Ricky Turcios draws a fun pairing against Aiemann Zahabi.