Those knees withstood the first week at the All England Club, and now it is over to the all-important second week as Rafael Nadal continues his quest for a third Wimbledon title.
His first opponent in week number two is Gilles Muller, the big-serving grass court specialist, capable of beating anyone on his day.
Muller has managed to get the better of Nadal at these very courts of Wimbledon, although that win came back in 2006, when the man from Luxembourg beat the Spaniard in the second round.
In their latest Wimbledon meeting, Nadal came through in three sets, two of them via tie-breakers, in the third round in 2011.
Nadal knows this match won't be an easy one, but he has backed himself to find the victory that he needs as long as he plays the same level of tennis as the first week, where he didn't drop a single set en route to the fourth round.
"He's one of the toughest opponents possible, on this surface especially," Nadal said. "This is his best surface without a doubt. He has a great serve, a great volley. He plays well from the baseline here.
"Yeah, he's a tough, tough opponent. At the same time we are in the round of 16. You cannot expect to have easy opponents. So is a very tough one because he played a lot on grass this year. He won, as you say, more than nobody, I think."
Nadal believes if he is to beat the serve-and-volley heavy Muller, he is going to have to serve really well throughout the match.
"It is true that is an opponent that has a special style, a lot of serve and volley, serving so good," the two-time champion added. "So going to be a very tough one. I need to be very focused with my serve and try to be aggressive on the return to try to have chances.
"But that's the second week. All the matches are difficult. Let's see if I am able to keep playing well."
Play well is what Muller has also done to get to the last 16, with the 34-year-old beating a couple of really difficult opponents to reach this stage. The No.16 seed, though, will know that level of tennis will need to go up a couple of notches if he is to cause an upset on "Manic Monday" at Wimbledon.
When and where to watch live
Nadal vs Muller is the second match on the No.1 Court, with the first one to begin at 1pm BST, 5.30pm IST, 2pm CET, 8am ET.
India: TV: Star Sports Select 2 and Star Sports Select 2HD. Live Streaming: Hotstar.
UK: TV: BBC One and BBC Two. Live Streaming: BBC iPlayer.
Spain: TV: Movistar+.
Asia: TV: Fox Sports Asia. Live Streaming: Fox Sports Play Asia.
Canada: TV: TSN, CTV. Live Streaming: TSN TV.
USA: TV: ESPN. Live streaming: Watch ESPN.
Australia: TV: Fox Sports. Live Streaming: Foxtel.
France and Middle East: TV: Bein Sports. Live Streaming: Bein Sports Connect.