Dimitrov G. vs Istomin D. prediction

Dimitrov is a huge favourite here, but I don't want to underestimate his rival. Dimitrov lost only set so far in this tournament but that was against world number 105 in the rankings Chung. Dimitrov had big problems against him after losoing the first set. On the other side Istomin is playing great so far here. Istomin defeated world number 2 Djokovic 3-2 sets. Istomin played two five sets battels in his last two matches. Head-to-head Dimitrov leads 1-0, clear win 2-0 sets two years ago, but at the moment Istomin shows great tennis and I think this will be another thriller. My pick is over 3.5 sets.