Stefanos Tsitsipas breezed into the third round of the Barcelona Open with a straight-sets win over Pedro Cachin on Wednesday.   Tsitsipas took 79 minutes to see off Argentine Pedro Cachin 6-4 6-2 on Pista Rafa Nadal.   The second seed from Greece did not face a break point and won all three that he fashioned to set up a meeting with Canadian Denis Shapovalov, who got the better of Jozef Kovalik 6-4, 6-3.   Jannik Sinner, the fourth seed from Italy, eased to a 6-2 6-4 win over Diego Schwartzman at the Real Club de Tennis Barcelona-1899.   Cameron Norrie and Lorenzo Musetti will do battle in round three after defeating Pavel Kotov and Jason Kubler respectively in straight sets.   Karen Khachanov beat Nicolas Jarry 6-4 6-4, while Grigor Dimitrov, Dan Evans, Alex de Minaur, Yoshihito Nishioka and Francisco Cerundolo also celebrated midweek wins.   Rain hit the schedule hard at the BMW Open, where Aslan Karatsev was leading Daniel Altmaie 3-0 in the third set when play was suspended in the only singles action of the day.