Michael Smith took his frustrations out on himself in painful fashion during his Grand Slam of Darts quarter-final defeat to Luke Humphries.The 2022 champion and 2023 PDC World Champion has been back in form in Wolverhampton, but his comeback was curtailed on Friday night by the world No.1.Smith began scratching his head and even drew bloodSkyBy the end of the match he had two clear red lines on his foreheadHumphries eventually eased to a 16-8 win, but Smith gave the crowd a show to make matters close earlier on.But as Cool Hand pulled back ahead, Smith could be seen feeling the pressure in a shockingly graphic way.The 35-year-old began scratching his forehead with his darts, producing a visible cut and blood.Legendary commentator and former professional Wayne Mardle commented: “He’s been doing that for years, I don’t know why he does it.”As Humphries closed in on victory, Smith had two visible red lines across his forehead.It left commentator Dan Dawson to state: “He’s been left battered and bruised and quite literally bloodied by Cool Hand.“Michael Smith when he is frustrated, when he is worried, when he is trying to figure things out on the dartboard, he will take the point of his dart and he scratches his forehead.“He has done that so much he has drawn blood.”Smith’s emotional Grand Slam rollercoaster It had already been an emotional week for Smith, who appears to finally be on the comeback trail after three years of struggles with form and injuries.Bullyboy progressed from a tough group including Humphries, and had to down top player Nathan Aspinall to make his way into the knockouts.Smith’s had a very emotional week upon his return to formAfter taking down ‘Asp’ he was asked about his struggles with injury by ViaPlay and began crying.“I just want to be competing,” he said, wiping away tears. “I’m sick of sitting at home watching people win tournaments, and I’m sat at home. It p***es me off. S*** happens, I guess.“Winning matches, that’s who I’m about, that’s Michael Smith, not sitting at home. Being on big stages listening to the crowds, that’s me.”Asked if he ever thought about retirement, he replied: “Not once. I think I made the semis of the UK Open with a hole in my leg.“I broke both my hands when I was 19, had casts for five months and then when I got them took off, within two weeks I won my first ProTour at 19. I’m a fighter, that’s it. I’ll be back, don’t worry.”