Many times throughout their glittering careers both Andy Murray and Novak Djokovic have breezed through the early rounds of major tournaments without even being tested.
Occasionally though, they are drawn against an opponent, who they know full well will give them a true test and a thorough run out, simply because they are very very big servers.
At Wimbledon yesterday afternoon and evening, both players were pushed very hard to guarantee their place in the last eight of this year's tournament.
BECOME A WRITER
Do you have what it takes? Sign up today and send over your 250 word test article: http://gms.to/haveyoursay3
Andy Murray was up against the 6ft 11ins Croat Ivo Karlovic, who boasted 136 aces in his first three matches of the tournament.
Murray employed a cute game plan, which involved a lot of lobs from deep when Karlovic came to the net, and also taking some pace off his first serve, so that he was able to get most of his first serves in, which meant Karlovic's return of serve was easier to get to.
Murray and Djokovic through
Eventually after just over three hours and a slight wobble in the third set Murray won in four sets, 7-6 (9-7) 6-4 5-7 6-4. Murray was quoted as saying by the Daily Mail: "It was an incredibly difficult match. It was mentally tiring, not physically as tiring but mentally as you've got to be ready for every single point".
As for Novak Djokovic the reigning champion, he had to battle hard for over three and three-quarter hours spread across two days before triumphing against the 6ft 8ins South African Kevin Anderson.
Djokovic lost the first two sets on Monday evening and fought back to level at two sets all before play was suspended on Monday evening due to bad light.
He came back on court on Tuesday afternoon and duly won the fifth and deciding set to earn a 6-7, 6-7, 6-1, 6-4, 6-4 victory and a quarter-final tie against Marin Cilic.
Although it is nice to see some big serving players do well in grand-slam tournaments, it is even better to see the better all-round players progress to the later rounds, as it is more of a game and much better entertainment for the spectators, rather than the crash bang wallop of the heavy servers.