Ajax defender Daley Blind allayed concerns over his health, insisting he is "okay and feeling fine" following a scare.
Blind is said to have collapsed before being substituted during Tuesday's 1-0 friendly win against Bundesliga opponents Hertha Berlin.
Former Manchester United utility Blind was fitted with a subcutaneous implantable cardioverter defibrillator – a device that monitors and regulates his heart rhythm – after being diagnosed with heart muscle inflammation following a Champions League game with Valencia last December.
The 30-year-old Netherlands international provided an update via social media on Wednesday, writing: "Many thanks for all the kind messages I've received.
"I can say that I'm okay and feeling fine."
Blind re-joined Dutch giants Ajax, where he began his career, in 2018 after spending four years with United in the Premier League.
Ajax are due to begin their Eredivisie season on September 13.
The 2019-20 campaign was suspended in March due to the coronavirus pandemic before being declared void a month later.