British rising star Jack Draper tested Spain's Rafael Nadal before physical issues hampered him in a four-set loss in the Australian Open first round.
Draper, 21, levelled at one-set each, leading to 22-time major champion Nadal, 36, having a frank discussion with his team before the third set.
Top seed Nadal led 4-1 but was still unconvincing as Draper broke back before the Briton lost serve at 5-4.
Draper struggled to move in the fourth as Nadal secured a 7-5 2-6 6-4 6-1 win.
Britain's Kyle Edmund was also knocked out on the opening day at Melbourne Park with a 6-4 6-0 6-2 defeat by Italian 15th seed Jannik Sinner.