Second-seeded Diego Schwartzman of Argentina produced hot streaks in both tiebreakers and emerged with a 7–6 (2), 7–6 (4) win over Spain’s Jaume Munar on Thursday in the second round of the Argentina Open in Buenos Aires. The first-set tiebreaker was level 2–2 before Schwartzman won the next five points. In the second-set tiebreaker, Schwartzman won the first six points. Munar then saved four match points before Schwartzman sealed the victory. Two more Argentinians joined Schwartzman in reaching the quarterfinals. Sixth-seeded Federico Delbonis defeated Spain’s Pablo Andujar 6–4, 6–4, and Francisco Cerundolo topped Serbia’s Miomir Kecmanovic 6–3, 3–6, 6–2. Fourth-seeded Fabio Fognini of Italy also advanced with a 6–4, 7–6 (5) victory over Spain’s Pedro Martinez. Dallas Open Both seeded U.S. players in action were pushed before advancing to the quarterfinals in Dallas. Second-seeded Reilly Opelka got past Germany’s Cedrik-Marcel Stebe 7–6 (3), 7–6 (8) as Stebe squandered two set …