 Complete the following phrase:  After WrestleMania, Lesnar turned his attention to John Cena, who had returned from injury in February 2003 after an F-5 into a ringpost from Lesnar, with Cena claiming that Lesnar nearly ended his career and even named his new finishing move the F.U. as a jab at the new champion. The feud ended in a match at Backlash on April 27, where Lesnar defeated Cena to retain the WWE Championship. On the following episode of SmackDown!, Lesnar returned to his rivalry with Big Show after, in the storyline, Big Show injured Rey Mysterio during their match at Backlash. Big Shows attack resulted in Mysterio being carried out on a stretcher and backboard, and Big Show took Mysterio off the stretcher and swung the backboard into the ringpost, compounding the injury. Lesnar called out Big Show, who demanded that Lesnar put his title on the line against him. This led to a stretcher match for the WWE Championship at 