Murray's law: Anything that went wrong before doesn't necessarily mean it will go wrong again.
A week ago, Andy Murray was hit with the onset of cramps in his hamstring, forearm and back, severely testing his ability to wrap up a U.S. Open first-round victory in four sets. Since then, he has performed far closer to the form that won him the 2012 Open and 2013 Wimbledon titles.
On Monday, Murray, despite suffocating heat and humidity, dispensed with Jo-Wilfried Tsonga, 7-5, 7-5, 6-4.
Tsonga beat Murray last month in Toronto. This time it was Tsonga, in their fourth-round match, who sweated so heavily that he said his shirt felt as if it weighed "2 kilograms" (that's nearly 4 1/2 pounds).
Tsonga committed as many double faults (six) as he had aces. At one point, he was assessed a fault when, just as he started his serve, he ducked and appeared to execute a half-swing because "a big bug came on my cap," Tsonga said.
Worse, for Tsonga, were his 43 unforced errors, compared to 18 in Murray's clean play.
Better, for Murray, was that he felt fine. "A week ago, I didn't feel great at all," he said. "Obviously, the first match was a big concern and now, a week later, I'm in the quarters. A lot can happen in a few days."
Not quite a year ago, Murray had back surgery after dealing with increasing pain. Back on the pro tour, he did not win any of his previous 13 tournaments in 2014.
In mid-August, during the Open tuneup tournament in Mason, Ohio, he said: "The focus is on winning now. Not so much how I'm hitting the ball or moving or anything like that. Just trying to win."
It was not as if his career was in ruins. But his ranking, up to No. 2 after last year's Wimbledon victory, had slipped to No. 9, which meant his Open seed makes his trip through the draw more difficult.
On top of that, he randomly landed in the same quarter of the bracket as No. 1 Novak Djokovic, whom Murray will play in Wednesday night's quarterfinal. Djokovic ensured that with a 6-1, 7-5, 6-4 win over No. 22 Philipp Kohlschreiber on Monday. No. 3 Stan Wawrinka also advanced against No. 16 Tommy Robredo.
What Murray's apparent building momentum signals, he cannot say. "Anything can happen in a couple of days," he said. "I don't feel I'm that far away from playing my best tennis. I mean, I played against some very good players this year and lost a few close matches. How big is this win? I don't really know, to be honest."
He does know "from experience," he said, "how hard it is to win one of these tournaments. I know how hard it is to go deep in them consistently, as well, because the level of the game now is extremely high."
But here's another rule of thumb for Murray: To duel the best is "really why we play the game," he said. "That's why you put the work in. As much as it's incredibly tough and challenging, that match is what you enjoy."
So though Djokovic leads 12-8 in their career head-to-head meetings (3-2 in majors), what mostly went right for Djokovic before might not again.