Scottish football witnessed major VAR controversy in the system's second game in use as Celtic edged a seven-goal thriller at Tynecastle.Hearts substitute Lawrence Shankland hit a hat-trick but was upstaged by the cinch Premiership leaders, who secured a 4-3 victory thanks to Greg Taylor's 76th-minute winner.FULL MATCH DETAILSJames Forrest, Giorgos Giakoumakis and Daizen Maeda also netted as the lead changed hands several times.A pulsating match was also overshadowed by some hotly debated decisions involving the newly introduced video technology.Decisions were confirmed by VAR checks during St Johnstone's win over Hibernian on Friday, but the first intervention came in first-half stoppage time across Edinburgh when referee Nick Walsh was told to look again at Cameron Carter-Vickers' challenge on Cammy Devlin by video assistant Steven McLean.Walsh went to his monitor to watch footage which clearly showed Devlin got the ball before being brought down.
Shankland netted from the spot to make it 1-1.Moments later Celtic appealed for a penalty when the ball hit Michael Smith's arm in the box after being flicked up by Forrest.
Walsh again played on and, after a much shorter delay while McLean checked the footage, the game continued.Smith had appeared to move his arm towards the ball and Celtic manager Ange Postecolgou could not believe the decision, laughing and clapping sarcastically.There was an earlier contentious decision as Anthony Ralston put the ball in the Hearts net which VAR confirmed, and the video official ordered a retake of the home team's second penalty of the day.The tone for the game was set early.