French Open champion Alexander Zverev revealed that a malfunctioning glucose sensor affected his performance during his Halle Open semi-final defeat to Taylor Fritz on Saturday.

The German entered the match with a difficult recent record against the American, having lost their previous six encounters. Despite the challenge, Zverev fought hard before eventually falling 6-7(4), 6-4, 7-5 after a two-hour and 39-minute battle.

Following the match, the world number three explained that problems with his glucose monitoring device caused him to mismanage his insulin levels during the contest.

“I had major issues with my blood sugar because the sensor I use gave me completely inaccurate readings. It showed extremely high levels when they were actually low, so I took far more insulin than I should have,” Zverev said.

He added that the situation made the match extremely difficult, saying he needed to consume around 350 grams of sugar during the opening 45 minutes just to manage the effects.

“I felt absolutely terrible,” the German star admitted.

Despite the setback, Alexander Zverev acknowledged that Taylor Fritz deserved the victory following their semi-final clash in Halle.

“Nevertheless, I fought, gave it my all, and in the end, it must also be recognised that Taylor Fritz deserved the win. He played better than me today,” Zverev said.

The German, who was diagnosed with Type 1 diabetes at the age of four, relies on Medtronic technology to help manage his glucose levels both on and off the court.

Zverev explained that the issue was highly unusual for him, noting that he has been using glucose sensors since 2016 or 2017 without experiencing a similar malfunction.

“This is the first time something like this has happened to me. I’ve been using these sensors for nine years and have never seen such a big error,” he said.

Despite the incident, Zverev added that he is not concerned about his condition ahead of Wimbledon, which runs from June 29 to July 12.