Ajax Amsterdam defender Daley Blind says he is "feeling fine" after he collapsed during Tuesday's pre-season friendly against Hertha Berlin when his implanted heart defibrillator momentarily switched off. The 30-year-old Netherlands defender dropped to the ground late in the game, which Ajax won 1-0 at the Johan Cruyff Arena, but was then able to walk off the pitch. "Many thanks for all the kind messages I received. I can say that I'm okay and feeling fine," Blind said on Twitter. The former Manchester United defender was diagnosed with heart muscle inflammation after experiencing dizziness in a Champions League game last year. He was fitted with an implantable cardioverter defibrillator (ICD) and returned to action in February. Ajax said in a statement that Blind would undergo further tests before resuming training. (For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)