Saw the first set. Pretty high quality shotmaking from both. Istomin just played a very loose game with overhead errors to get broken. Benne looked very solid, moving the ball well, hitting winners, finding angles, some good net points.
I remember him taking a set off Roddick a few years ago, and should have won the match. If he can stay mentally strong, should have a big shot. That's a massive if with him though.
Mental toughness is a big weakness in istomin's game. He has the shots and serve, but he mentally drifts away in important stages of the match. Also, his footwork has never been the best but it's not the reason why these matches slip away from him.