MELBOURNE – Up there above the clouds, near the peak of Mount Everest which is at 8,848m, mountaineers are confronted with one last obstacle. A 12m rock face at 8,790m named the Hillary Step. By the time climbers reach there they are exhausted and the face demands fine technical skills. It is a stern reminder from the mountain that there is always more to do.

On Rod Laver Arena on Thursday night, as a 12th seed outsider from China played a world No. 93 underdog from Ukraine, the summit looked close. But these last steps are always the hardest, especially for those not used to the thin air of Grand Slam semi-finals. The result, almost understandably, was a slightly hiccuping match, full of heavy-hitting, some of it reckless. For once both players, Zheng Qinwen and Dayana Yastremska, knew there was a lot to lose.