MELBOURNE, Australia — It was difficult to tell who was more pleased with reaching the Australian Open semifinals: Djokovic was simply overpowering as he beat Canadian Milos Raonic 7-6 (5), 6-4, 6-2 in exactly two hours at Rod Laver Arena in a night match on Wednesday, never facing a break point. The four-time champion, who has dropped his serve only once through five matches, will face defending champ Stan Wawrinka on Friday. Keys overcame a left thigh injury to beat Venus Williams 6-3, 4-6, 6-4, and will next play a five-time Australian champ also named Williams — top-seeded Serena — on Thursday. Keys, who said watching the Williams sisters inspired her to take up tennis, talked about the sheer thrill of being in the final four of a major for the first time. There had been some hope that the semis might feature an all-Williams matchup at a major for the first time since the 2009 Wimbledon final. Venus’ loss ended an encouraging 10 days for the seven-time Grand Slam singles champion. “It feels like a long season already, so many matches in a row,” said Williams, who won the WTA event in Auckland to open the year. Wawrinka beat U.S.