Djokovic struggled as the first set went on, grimacing in pain and pulling up on his leg. He received treatment after Alcaraz broke to lead 5-4 and, when he returned, quickly lost the opening set.
His physical problems persisted in the second set and the No. 7 seed continued to wince in pain. But he kicked into life at the perfect time, breaking at the end to snatch the set and level the score.
Djokovic continued to raise his level and there were no longer any signs of injury – apart from when he took two more painkillers during the fourth set. Afterwards, the 10-time champion addressed his physical concerns and confessed that he almost quit the match.
“Well since I’m still in the tournament, I don’t want to reveal too much obviously,” Djokovic started. “But yeah, the medication started to kick in and that helped, no doubt. I had to take another dose. This sounds awful! Me taking another dose. But I had to.
“I didn’t know, to be honest, if I lost the second set I didn’t know if I would continue playing. But I felt better and better, managed to play a great couple of games to end the second set.”
Djokovic was also encouraged when he saw Alcaraz’s level begin to drop. By the end of the match, he felt fine.
He continued: “And then I saw that Carlos was hesitant a little bit from the back of the court and I took my chances and started to feel better, started to move better. So it didn’t bother me, it didn’t create any hindrance towards the end of the match, only in that second set.”
However, the world No. 7 may not be in the clear just yet. “Obviously when the medication starts to release, I’ll see what the reality is tomorrow morning. But right now I’ll just try to be in the moment and enjoy this victory,” he said, hinting that Friday’s semi-final was up in the air.
MORE TO FOLLOW
We’ll be bringing you the very latest updates, pictures and video on this breaking news story.
For the latest news and breaking news visit: express.co.uk/sport/football. Stay up to date with all the big headlines, pictures, analysis, opinion and video on the stories that matter to you.
Follow us on Twitter @dexpress_sport – the official Daily Express & Express.co.uk Twitter account – providing real news in real time.
We’re also on Facebook @dailyexpresssport – offering your must-see news, features, videos and pictures throughout the day to like, comment and share from the Daily Express, Sunday Express and Express.co.uk.

