Juan Martin del Potro played through the pain barrier to reach his first Wimbledon semi-final as the former US Open champion defeated Spanish fourth seed David Ferrer 6-2, 6-4, 7-6 (7/5) on Wednesday.
Argentine eighth seed Del Potro emerged unscathed despite a nasty fall in the first game of the quarter-final that required several minutes' treatment and briefly appeared to leave him in tears.
The 24-year-old was clearly struggling to move at times, but he gritted his teeth through two hours and 16 minutes of gruelling action, unloading 42 winners and 12 aces to finally subdue the battling Spaniard.
Del Potro's reward for his heroic efforts is a daunting clash against world number one Novak Djokovic on Friday for a place in Sunday's final.
It will be del Potro's first Grand Slam semi-final appearance since his breakthrough triumph at the US Open four years ago.
Del Potro is just the second Argentine man to feature in the Wimbledon semi-finals, following in the footsteps of David Nalbandian in 2002.
Asked how close he was to pulling out, he said: "Really close because I felt a lot of pain in the beginning of the match. It was exactly the same like I did before. It's really, really painful. I twisted my knee once again but the doctor gave me some magic pills so I could finish the match and I'm so glad to go through.
"I think I played my best tennis in this match. I hit really well my forehand, my serves and in the end I played my best forehand ever in this Wimbledon -- I was lucky that that ball was in and I won the match."
This was del Potro's first appearance in the last eight at Wimbledon, but he took the bronze medal at last year's London Olympics, played at the All England Club, after beating Djokovic in the third place match and now he has avenged his last 16 loss to Ferrer at Wimbledon 12 months ago.
Reports just before the start of the quarter-final suggested Ferrer had struggled so badly with ankle and toe injuries that he could only practise for a couple of minutes on Wednesday morning before seeking out a doctor.
Ironically it was del Potro who suffered the more serious injury scare after just four points.
Leading 40-15 on Ferrer's serve, del Potro stretched to reach a shot on the baseline and took a nasty fall which bent his left leg at an awkward angle.
It was del Potro's left knee, already heavily strapped after a previous injury earlier in the tournament, that the doctor focused on but the Argentine opted to keep playing.
Incredibly it was a limping del Potro who broke in the third game and then again in the seventh before serving out the set.
Del Potro kept slugging away from the baseline, putting enough pressure on Ferrer to take the second set as well after breaking for a 5-4 lead when the Spaniard netted a backhand.
The Argentine was still made to sweat by the relentless Ferrer, but the del Potro finally delivered the knockout blow in the third set tie-break with a brilliant forehand winner on the run.