Harder than he should have.
Murray put in a ragged, labored performance Wednesday against an opponent who had played 14 sets in his previous three matches in Melbourne. His first-serve percentage was under 50, he was plus-four in the winners-to-unforced-errors count through two sets, and he allowed the entertaining Japanese baseliner to do too much of the dictating.
The first set lasted nearly an hour and the second set was almost as long. Still, the outcome was never in doubt, and the bottom line was a 6-3, 6-3, 6-1 Murray victory that sent the Scot into the semifinals against Novak Djokovic.
Not in the script: For Nishikori to have a chance of beating Murray, he had to win that first set. But he didn't. And his start was poor. Trailing 1-0, Nishikori raced to a 40-0 lead on serve. He was, though, eventually broken for 2-0. Then Nishikori couldn't convert two break points in the third game. Murray was on his way, although he survived three break points at 4-2.
Murray's early TKO: Murray likes playing those long points in Melbourne, doesn't he? In last year's final, he and Djokovic took part in a draining 39-shot rally. Djokovic prevailed. Murray and Nishikori went to 42 in the second game, and there was only going to be one winner: Murray. He is in better shape than Nishikori and ended the point with a short backhand that Nishikori didn't bother to chase.
Another one: The 'tweeners keep on coming. Nishikori struck one in the fourth game of the first set countering a lob, and it was a peach. Murray backpedaled at the net but couldn't get much on his smash. Nishikori duly ripped a short forehand into the corner for a winner before pumping his fist. His shot between the legs trumped the efforts of Djokovic and Juan Martin del Potro. Murray's attempted 'tweener in reply to a smash late in the first was highly creative.
Not a Nico moment: Murray had a short ball at 3-2 in the second set off a netcord. With Nishikori stranded at the net, it looked like Murray was lining up to hit straight at him. But Murray isn't that sort, and he hooked his cross-court forehand.
Great pickup: Murray displayed his great hands to start the third. He picked off a Nishikori shot at the baseline and sent his forehand half-volley reply cross court for a winner. The crowd gasped.
Good omen for Andy: Murray reached his third consecutive semifinal at the Australian Open. The deeper meaning? He was the ninth man to do it, and the previous eight all ended up as Grand Slam champions.
What's next for Andy: Murray will indeed face Djokovic. Murray's foes in the third and fourth round, as well as Nishikori, had gone five sets in their previous matches. Djokovic didn't need to go five to fend off David Ferrer in Wednesday's night session, but the breathing issues appeared to have returned. Are the stars aligning for Murray?
Nice tournament, Kei: If he can stay healthy, Nishikori will keep movin' on up. After reaching his first Grand Slam quarterfinal, he's expected to climb to No. 20, a new personal best. There's more to come.
London-based Ravi Ubha covers soccer and tennis for ESPN.com. You can follow him on Twitter.