WATCH: Holger Rune suffers what could be career-altering injury in Stockolm

Holger Rune sustained what might be the worst moment of his career when he pulled up at the 2025 Stockholm Open.

The Dane faced Ugo Humbert in the semifinal. He still had an outside chance of qualifying for the 2025 ATP Finals, and reaching the final in Stockholm could have been pivotal to those hopes.

Rune played really well in the opening set against Humbert, one of the best indoor hard-court players on the ATP Tour. The 22-year-old took it 6-4 and looked a heavy favorite to make the final at that stage.

Sadly, Rune's horrific moment occurred with the score at 2-2 in the second set. During a rally, he suddenly pulled up and started limping. It was not immediately evident how severe that issue was.

The extent of the problem became clearer when Rune cried while sitting down after the physio had inspected it. From that reaction and the physio's inspection, an issue with the young star's Achilles seemed likely.

After Rune's tears, the inevitable happened when the umpire announced his retirement from the match, handing Humbert a place in the final in a manner the Frenchman definitely did not want.

Rune needed two people to help him off the court. The Swedish fans applauded him off, and Rune, to his immense credit, considering his devastation at the injury, waved at them in appreciation for their support.

Fans' worst fears were realized when Aneke, Holger's mother, confirmed in a text message to Ekstra Bladet that her son's problem looked like a torn Achilles tendon, which would need surgery.

Aneke estimated that Holger would be out for approximately six months. If true, that could alter the direction of Rune's career, since lengthy injuries can sometimes set players back a long way in their development.

Missing six months would be devastating, but the effect usually continues after that, since players who spend a lengthy period on the sidelines often take several more months to get back to their old level.

Rune had already slipped behind Carlos Alcaraz and Jannik Sinner, raising concerns about his inability to maximize his talent. This moment will make that even more challenging for the 2022 Paris Masters Champion.

At the 2025 Six Kings Slam, Alcaraz confidently said that he was not in his prime yet. If the ATP world No. 1 improves more while Rune is out injured, it will be even more challenging for the Dane to challenge him.

In his 2025 Wimbledon quarterfinal against Sinner, Dimitrov was leading 6-3, 7-5, 2-2 against the eventual champion when he suddenly shouted in pain and stopped playing to receive treatment.

The Bulgarian tore a chest muscle and could not continue. It was an utterly heartbreaking moment for the 34-year-old, who may have lost his best chance of reaching a Grand Slam final.

Dimitrov is still recovering from that injury. He split from his coach, Jamie Delgado, despite their successful collaboration for close to three years.