Cape Town - Not often 6ft 8in Kevin Anderson has to look up to an opponent on the tennis court.
But it happened in more ways than one when the top South African tennis player suffered a shock 6-7 (5/7), 6-3, 7-5 defeat against up-and-coming, 6ft 11in US prospect Reilly Opelka in his opening game of the Atlanta Open on Wendesday.
The 18-year-old, lethal-serving Opelka went into the match ranked 556th in the world against the 28th-ranked Anderson and secured his first-ever victory against a player ranked among the top 30 in the world.
And weighing in at 96kg on the scales, in addition to his formidable height, the American youngster, who won the Wimbledon junior title last year, clearly looks to be developing into a formidable tennis force in the future.
As for Anderson, it was another jarring setback during what has generally been a downward slide to his tennis career in 2016.
After showing signs of a recovery in his previous tournament in which he reached the quarter-finals of the Toronto Masters, Anderson again displayed a wavering temperament in losing matches in which he appeared to be in control.
Against Opelka, the third seed failed to come out on top in spite of having two match points on his own powerful service in the third set - to suggest that his string of modest results are having a detrimental impact on his confidence.
And with the US Open in which he reached his only Grand Slam quarter-final last year looming at the end of the month, the string of upsets against lower-ranked opponents would seem a cause for genuine concern.
Of minor compensation for Anderson's early exit in Atlanta is the fact this his 28th world ranking is not likely to deteriorate next week - and could ironically improve because the majority of top players are either participating in the Olympic Games or are out of action because of injuries.