Matteo Berrettini caused an upset on Thursday when he beat Karen Khachanov in the second round of the Stuttgart Open. The 23-year-old Italian overcame the Russian second seed 6-4, 6-2 in 69 minutes. Last month at the Italian Open, Berrettini beat world number five Alexander Zverev 7-5, 7-5 in the second round. Berrettini broke Khachanov at 3-3 in the first set and then in the first game of the second set. Berrettini closed out the match with a 60-second service hold. Berrettini will meet Denis Kudla in the quarter-finals after the American knocked out French fifth seed Gael Monfils.