World number three Alexander Zverev on Thursday defeated Pablo Carreno Busta 6-2, 7-5 to reach the quarter-finals of the ATP Masters 1000 tournament in Monte Carlo. "To win the biggest tournaments in the world, like Masters series, like Grand Slams, you have to be aggressive," the 24-year-old German said. Zverev reached the quarter-finals in Monte Carlo for the second time.